60 changed files with 263 additions and 2498 deletions
--- a/README.md
+++ b/README.md
@ -41,25 +41,6 @@ Other inspirations were, among others, in no particular order:
 - the Magic-1 by Bill Buzbee
 - the OPC by revaldinho

-## October 2025 Update
-This update introduces a data cache for the Tridora-CPU. It is similar to the instruction cache
-as it caches the 16 bytes coming from the DRAM memory controller. It is a write-back cache, i.e.
-when a word inside the cached area is written, it updates the cache instead of invalidating it.
-
-This is important because there are many idioms in the stack machine assembly language where you
-store a local variable and then read it again (e.g. updating a loop variable).
-
-Since for most programs, the user stack and parts of the heap are inside the DRAM area, the data cache
-has a more noticable impact. In the benchmark program that was already used for the last update,
-the data cache results in a 50% improvement for the empty loop test. This is in comparison to the version
-without data cache but with the instruction cache, both running code out of DRAM.
-
-It is also noticable for compile times: With the data cache, compiling and assembling the
-"hello,world" program takes 16 seconds instead of 20. With a little tweak of the SD-Card controller
-that slightly increased the data transfer rate, the build time goes down to 15 seconds.
-
-Also, an audio controller was added that allows interrupt-driven sample playback via an AMP2 PMOD.
-
 ## April 2025 Update
 The clock has been reduced to 77 MHz from 83 MHz. Apparently the design was at the limit and
 timing problems were cropping up seemingly at random. Reducing the clock speed made some
@ -81,7 +62,7 @@ on the emulator image.
 - the [Hackaday project](https://hackaday.io/project/198324-tridora-cpu) (mostly copy-paste from this README)
 - the [YouTube channel](https://www.youtube.com/@tridoracpu/videos) with some demo videos
 - the [emulator](https://git.insignificance.de/slederer/-/packages/generic/tridoraemu/0.0.5/files/12) (source and windows binary)
- the [FPGA bitstream](https://git.insignificance.de/slederer/-/packages/generic/tdr-bitstream/0.0.4/files/16) for the Arty-A7-35T board
+- the [FPGA bitstream](https://git.insignificance.de/slederer/-/packages/generic/tdr-bitstream/0.0.2/files/14) for the Arty-A7-35T board
 - an [SD-card image](https://git.insignificance.de/slederer/-/packages/generic/tdr-cardimage/0.0.4/files/13)

 Contact the author here: tridoracpu [at] insignificance.de
--- a/doc/irqctrl.md
+++ b/doc/irqctrl.md
@ -9,13 +9,12 @@ The interrupt controller uses a single register at address: $980

 |_bit_  |15|14|13|12|11|10|09|08|07|06|05|04|03|02|01|00|
 |-      |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |
-|_Value_|t |t |t |t |t |t |t |t |- |- |- |- |- |p2 |p1 |p0 |
+|_Value_|t |t |t |t |t |t |t |t |- |- |- |- |- |- |p1 |p0 |


 |Bitfields|Description|
 |---------|-----------|
 | _t_     | unsigned 24 bit counter of timer ticks since reset
-| _p2_    | IRQ 2 (audio) interrupt pending if 1
 | _p1_    | IRQ 1 (timer tick) interrupt pending if 1
 | _p0_    | IRQ 0 (UART) interrupt pending if 1

--- a/doc/mem.md
+++ b/doc/mem.md
@ -34,4 +34,3 @@ Currently, only I/O slots 0-3 are being used.
 | 1      | $880    | SPI-SD     |
 | 2      | $900    | VGA        |
 | 3      | $980    | IRQC       |
-| 4      | $A00    | TDRAUDIO   |
--- a/doc/pascalprogramming.md
+++ b/doc/pascalprogramming.md
@ -103,16 +103,6 @@ Tridora-Pascal only supports the _break_ statement at the moment.
 The _exit_ statement can be used to exit the current procedure or function. If it is a function, the return value of the function is undefined if _exit_ is
 used before a return value is assigned.

-
-## Dynamic Memory Allocation
-Memory allocation generally works as expected with the *new* and *dispose* special procedures. The variant of *new* with two parameters that is specified in Wirth Pascal is not supported (partial allocation of a variant record). Instead, there is a variant of *new* that has a second parameter for allocating strings (see above).
-
-If heap allocation fails, *new* does not return and instead causes a runtime error. To avoid this, a different special procedure called *newOrNil* can be used. This procedure sets the pointer
-variable to *niL* if heap allocation fails.
-
-The function *MemAvail* returns the number of free bytes on the heap. It does not guarantee that this amount of memory can be allocated with *new*, because heap space can be fragmented.
-The function *MaxAvail*, which exists in some versions of Turbo Pascal and returns the size of the largest contiguous block of available heap memory, is not (yet) implemented.
-
 ## I/O
 I/O handling in Tridora Pascal is mostly compatible with other Pascal dialects when reading/writing simple variables from/to the console. There are big differences when opening/reading/writing files explicitly.

@ -163,12 +153,10 @@ var f:file;
 ### Error Handling
 When an I/O error occurs, the _IOResult_ function can be called to get the error code. Unlike TP, the _IOResult_ function requires a
 file variable as a parameter. When you call _IOResult_, an error that may have occurred is considered to be _acknowledged_. If an
-error is not ackowledged and you do another I/O operation on that file, a runtime error is thrown.
+error is not ackowledged and you do another I/O operation, a runtime error is thrown.

 That means you can either write programs without checking for I/O errors, while resting assured that the program will exit if an I/O error occurs. You can also choose to check for errors with _IOResult_ if you want to avoid having runtime errors.

-If an I/O error occurs on a file, it is then considered closed. Closing a file in this state, or a file that has been closed normally, will cause a runtime error.
-
 The function _ErrorStr_ from the standard library takes an error code as an argument and returns the corresponding textual description as a string.

 Example:
@ -203,8 +191,7 @@ Possible error codes from _IOResult_ are:
 | 8 | IOReadOnly        | file is readonly |  |
 | 9 | IOInvalidOp       | invalid operation |  |
 | 10 | IOInvalidFormat   | invalid format | when parsing numbers with _read_ |
-| 11 | IONoMem   | not enough memory | heap allocation failed inside the standard library, e.g. open() |
-| 12 | IOUserIntr        | interrupted by user | program terminated by ^C, not visible from _IOResult_ |
+| 11 | IOUserIntr        | interrupted by user | program terminated by ^C, not visible from _IOResult_ |

 ### Read, Readln and Line Input
 In Turbo Pascal, using _read_ (and _readln_) from the console always waits until a complete line has been entered.
--- a/doc/tdraudio.md
+++ b/doc/tdraudio.md
@ -1,104 +0,0 @@
-# Audio Controller
-The audio controller provides four channels of 16-bit PCM audio playback.
-
-It uses multiple registers starting at address $A00.
-
-Each of the four channels has three registers.
-
-For the first channel the register addresses are:
-
-|Address|Description|
-|-------|-----------|
-| $A00  | Control Register |
-| $A01  | Clock Divider Register |
-| $A02  | Amplitude Register |
-
-The register addresses for the second channel start at $A04,
-the third channel at $A08
-and the fourth channel at $A0C.
-
-## Reading the control register
-
-|_bit_  |31|30|29|28|27|26|25|24|23|22|21|20|19|18|17|16|
-|-      |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |
-|_Value_|- |- |- |- |- |- |- |- |- |-|- |- |- |- |- |- |
-
-|_bit_  |15|14|13|12|11|10|09|08|07|06|05|04|03|02|01|00|
-|-      |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |
-|_Value_|- |- |- |- |- |- |- |- |- |- |- |i |f | e | p | c |
-
-
-|Bitfields|Description|
-|---------|-----------|
-| _i_    | interrupt is enabled for this channel when 1 |
-| _f_    | sample buffer is full when 1 |
-| _e_    | sample buffer is empty when 1 |
-| _p_     | changes from 0 to 1 and vice versa on each sample clock |
-| _c_     | channel is enabled if 1 |
-
-## Writing the control register
-
-|_bit_  |31|30|29|28|27|26|25|24|23|22|21|20|19|18|17|16|
-|-      |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |
-|_Value_|- |- |- |- |- |- |- |- |- |-|- |- |- |- |- |- |
-
-|_bit_  |15|14|13|12|11|10|09|08|07|06|05|04|03|02|01|00|
-|-      |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |
-|_Value_|- |- |- |- |- |- |- |- |- |- |- |i |- | - | - | c |
-
-
-|Bitfields|Description|
-|---------|-----------|
-| _c_     | enable channel if 1, disable if 0 |
-| _i_     | enable channel interrupt if 1, disable if 0 |
-
-
-## Writing the clock divider register
-
-|_bit_  |31|30|29|28|27|26|25|24|23|22|21|20|19|18|17|16|
-|-      |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |
-|_Value_|d |d |d |d |d |d |d |d |d |d|d |d |d |d |d |d |
-
-|_bit_  |15|14|13|12|11|10|09|08|07|06|05|04|03|02|01|00|
-|-      |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |
-|_Value_|d |d |d |d |d |d |d |d |d |d|d |d |d |d |d |d |
-
-
-|Bitfields|Description|
-|---------|-----------|
-| _d_     | an unsigned 32-bit value for the clock divider |
-
-
-## Writing the amplitude register
-
-|_bit_  |31|30|29|28|27|26|25|24|23|22|21|20|19|18|17|16|
-|-      |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |
-|_Value_|- |- |- |- |- |- |- |- |- |-|- |- |- |- |- |- |
-
-|_bit_  |15|14|13|12|11|10|09|08|07|06|05|04|03|02|01|00|
-|-      |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |- |
-|_Value_|a |a |a |a |a |a |a |a |a |a |a |a |a | a | a | a |
-
-
-|Bitfields|Description|
-|---------|-----------|
-| _a_     | an unsigned 16-bit value for the amplitude (sample) value with a bias of 32768 |
-
-## Notes
-The clock divider specifies the number of CPU clock ticks between two samples.
-
-Writing to the amplitude register adds the sample value to the sample buffer. The sample buffer is organized as a FIFO with 16 elements.
-
-Amplitude (sample) values are represented as unsigned, biased 16-bit numbers. The bias is 32768, so given an amplitude range of 1.0 to -1.0, a 1.0 is represented by 65535, 0.0 by 32768 and -1.0 by 0.
-
-Interrupt processing needs to be enabled for each channel if required.
-
-An interrupt on any channel will be signalled to the interrupt controller
-as IRQ 2. The interrupt service routine should check all running channels
-for an emtpy buffer.
-
-If an audio interrupt has occured on a channel, the interrupt enable flag
-is cleared for that channel. It needs to be re-enabled in the interrupt service routine.
-
-Interrupts also need to be enabled on the interrupt controller,
-and re-enabled there after each interrupt.
--- a/examples/LICENSES.md
+++ b/examples/LICENSES.md
@ -7,9 +7,4 @@ https://commons.wikimedia.org/wiki/File:Ara-Zoo-Muenster-2013.jpg
 https://commons.wikimedia.org/wiki/File:Snow_leopard_portrait.jpg
 * shinkansen.pict: 投稿者が撮影, CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3.0/>, via Wikimedia Commons
 https://commons.wikimedia.org/wiki/File:0key22-86.JPG 
-* Toco_Toucan.pict: Bernard DUPONT, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons
-https://commons.wikimedia.org/wiki/File:Toco_Toucan_(Ramphastos_toco)_-_48153967707.jpg
-* 1911_Detroit_Electric.pict: Cullen328, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
-https://commons.wikimedia.org/wiki/File:1911_Detroit_Electric.jpg
-* ADDS-Envoy-620.pict: ADDS Envoy-1.jpg from terminals-wiki.org, CC-BY-SA 3.0
-https://terminals-wiki.org/wiki/index.php/File:ADDS_Envoy-1.jpg
+
--- a/examples/Toco_Toucan.pict
+++ b/examples/Toco_Toucan.pict
--- a/examples/animate.pas
+++ b/examples/animate.pas
@ -1,164 +0,0 @@
-program animate;
-uses sprites;
-
-type PictData = record
-		magic,mode:integer;
-		palette: array [0..15] of integer;
-		pixeldata: array [0..31999] of integer;
-	end;
-
-     Sprite = record
-     	x,y:integer;
-     	oldX,oldY:integer;
-     	xdelta,ydelta:integer;
-     	curFrame:integer;
-     	frameCount:integer;
-     	frameTime:integer;
-     	frameLeft:integer;
-     	changed:boolean;
-     	frame:array [0..3] of SpritePixels;
-    end;
-
-var pic:PictData;
-    filename:string;
-    infile:file;
-    ch:char;
-    stickMan:Sprite;
-    rocket:Sprite;
-
-procedure WaitVSync; external;
-
-procedure loadPalette(var pic:PictData);
-var i:integer;
-begin
-	for i := 0 to 15 do
-		setpalette(i, pic.palette[i]);
-end;
-
-procedure showPic(var pic:PictData);
-begin
-	PutScreen(pic.pixeldata);
-end;
-
-procedure loadSpriteFrame(var aSprite:Sprite;spriteIndex:integer;
-		var sheetFile:file;sheetIndex:integer);
-begin
-	seek(sheetFile, 8 + sheetIndex * 512);
-	read(sheetFile, aSprite.frame[spriteIndex]);
-	if aSprite.frameCount <= spriteIndex then
-		aSprite.frameCount := spriteIndex + 1;
-
-	aSprite.curFrame := 0;
-	writeln('loaded sprite frame ', spriteIndex, ' from ', sheetIndex);
-end;
-
-procedure animateSprite(var aSprite:Sprite);
-var frameIndex:integer;
-    frameTime,frameLeft:integer;
-    ydelta:integer;
-    oldX,oldY:integer;
-begin
-	ydelta := aSprite.ydelta;
-	frameIndex := aSprite.curFrame;
-	frameTime := aSprite.frameTime;
-	frameLeft := aSprite.frameLeft;
-	oldX := aSprite.x; oldY := aSprite.y;
-	aSprite.oldX := oldX; aSprite.oldY := oldY;
-
-	frameLeft := frameLeft - 1;
-	if frameLeft <= 0 then
-	begin
-		frameIndex := frameIndex + 1;
-		frameLeft := aSPrite.frameTime;
-		aSprite.frameLeft := frameLeft;
-		aSprite.curFrame := frameIndex;
-		if frameIndex >= aSprite.frameCount then
-			aSprite.curFrame := 0;
-
-		aSprite.frameLeft := frameLeft;
-
-		aSprite.x := aSprite.x + aSprite.xdelta;
-		aSprite.y := aSprite.y + aSprite.ydelta;
-
-		if aSprite.x > 608 then aSprite.x := 0;
-
-		if aSprite.y < 0 then
-		begin
-			aSprite.y := 200;
-			aSprite.x := 0;
-		end;
-	end;
-	aSprite.frameLeft := frameLeft;
-end;
-
-procedure animLoop;
-var i:integer;
-    oldX,oldY:integer;
-    roldX,roldY:integer;
-begin
-	stickMan.x := 0;
-	stickMan.y := 310;
-	stickMan.frameTime := 6;
-	stickMan.frameLeft := stickMan.frameTime;
-	stickMan.curFrame := 0;
-	stickMan.xdelta := 2;
-	stickMan.ydelta := 0;
-
-
-	rocket.x := 0;
-	rocket.y := 200;
-	rocket.frameTime := 1;
-	rocket.frameLeft := rocket.frameTime;
-	rocket.curFrame := 0;
-	rocket.xdelta := 2;
-	rocket.ydelta := -1;
-
-	while not ConAvail do
-	begin
-		oldX := stickMan.x;
-		oldY := stickMan.y;
-
-		roldX := rocket.x;
-		roldY := rocket.y;
-
-		PutSprite(roldX, roldY, rocket.frame[rocket.curFrame]);
-		PutSprite(oldX, oldY, stickMan.frame[stickMan.curFrame]);
-
-		animateSprite(rocket);
-		animateSprite(stickMan);
-
-		{Delay(1);}
-		WaitVSync;
-
-		UndrawSprite(oldX, oldY, pic.pixeldata);
-		UndrawSprite(roldX, roldY, pic.pixeldata);
-	end;
-end;
-
-begin
-	filename := 'background.pict';
-	open(infile, filename, ModeReadonly);
-	read(infile, pic);
-	close(infile);
-
-	writeln('magic: ', pic.magic, ' mode:', pic.mode);
-
-	loadPalette(pic);
-	showPic(pic);
-
-	open(infile, 'walking.sprt', ModeReadOnly);
-	loadSpriteFrame(stickMan, 0, infile, 0);
-	loadSpriteFrame(stickMan, 1, infile, 1);
-	loadSpriteFrame(stickMan, 2, infile, 2);
-	loadSpriteFrame(stickMan, 3, infile, 3);
-	close(infile);
-
-	open(infile, 'rocket.sprt', ModeReadOnly);
-	loadSpriteFrame(rocket, 0, infile, 0);
-	loadSpriteFrame(rocket, 1, infile, 1);
-	loadSpriteFrame(rocket, 2, infile, 2);
-	loadSpriteFrame(rocket, 3, infile, 3);
-	close(infile);
-
-	animLoop;
-end.
--- a/examples/background.pict
+++ b/examples/background.pict
--- a/examples/benchmarks.results.text
+++ b/examples/benchmarks.results.text
@ -45,7 +45,6 @@ Running benchmarks.prog
                          exp() 10K 00:00:29
                          cos() 10K 00:00:06

--------------------------------------
 Arty-A7-35T
 76.92MHz, 64KB SRAM, 256MB DRAM
 running in DRAM (except corelib, stdlib, runtime)
@ -69,7 +68,7 @@ Running benchmarks.prog
                          exp() 10K 00:00:32
                          cos() 10K 00:00:06

--------------------------------------
+
 Arty-A7-35T
 76.92MHz, 64KB SRAM, 256MB DRAM, 16B instruction cache
 running in DRAM (except corelib, stdlib, runtime)
@ -92,105 +91,3 @@ Running benchmarks.prog
                 array copy 128k 1K 00:00:48
                          exp() 10K 00:00:32
                          cos() 10K 00:00:06
-
--------------------------------------
-Arty-A7-35T
-76.92MHz, 64KB SRAM, 256MB DRAM,
-  16B instruction cache, 16B wt data cache
-running in SRAM
-
-Running benchmarks.prog
-                     empty loop 10M 00:00:07
-                 write variable 10M 00:00:17
-                  read variable 10M 00:00:20
-               integer addition 10M 00:00:20
-                   real addition 1M 00:00:28
-          integer multiplication 1M 00:01:11
-             real multiplication 1M 00:00:59
-                integer division 1M 00:01:36
-                   real division 1M 00:01:05
-                 string indexing 1M 00:00:39
-                string iteration 1M 00:00:19
-                  new/dispose 1k 1M 00:00:19
-                new/dispose 128k 1M 00:00:19
-                  array copy 1k 10K 00:00:03
-                 array copy 128k 1K 00:00:39
-                          exp() 10K 00:00:26
-                          cos() 10K 00:00:05
-
-
-
--------------------------------------
-Arty-A7-35T
-76.92MHz, 64KB SRAM, 256MB DRAM,
-  16B instruction cache, 16B wb data cache
-running in SRAM
-
-Running benchmarks.prog
-                     empty loop 10M 00:00:04
-                 write variable 10M 00:00:11
-                  read variable 10M 00:00:18
-               integer addition 10M 00:00:18
-                   real addition 1M 00:00:27
-          integer multiplication 1M 00:00:49
-             real multiplication 1M 00:00:58
-                integer division 1M 00:01:06
-                   real division 1M 00:01:04
-                 string indexing 1M 00:00:36
-                string iteration 1M 00:00:19
-                  new/dispose 1k 1M 00:00:18
-                new/dispose 128k 1M 00:00:18
-                  array copy 1k 10K 00:00:03
-                 array copy 128k 1K 00:00:39
-                          exp() 10K 00:00:25
-                          cos() 10K 00:00:05
-
--------------------------------------
-Arty-A7-35T
-76.92MHz, 32KB SRAM, 256MB DRAM,
-  16B instruction cache, 16B wb data cache
-running in SRAM
-
-Running benchmarks.prog
-                     empty loop 10M 00:00:04
-                 write variable 10M 00:00:11
-                  read variable 10M 00:00:18
-               integer addition 10M 00:00:18
-                   real addition 1M 00:00:27
-          integer multiplication 1M 00:00:49
-             real multiplication 1M 00:00:58
-                integer division 1M 00:01:06
-                   real division 1M 00:01:04
-                 string indexing 1M 00:00:36
-                string iteration 1M 00:00:19
-                  new/dispose 1k 1M 00:00:18
-                new/dispose 128k 1M 00:00:18
-                  array copy 1k 10K 00:00:03
-                 array copy 128k 1K 00:00:39
-                          exp() 10K 00:00:25
-                          cos() 10K 00:00:05
-
--------------------------------------------
-Arty-A7-35T
-76.92MHz, 64KB SRAM, 256MB DRAM,
-  16B instruction cache, 16B wb data cache
-running in DRAM (except corelib, stdlib, runtime)
-
-Running benchmarks.prog
-                     empty loop 10M 00:00:10
-                 write variable 10M 00:00:11
-                  read variable 10M 00:00:11
-               integer addition 10M 00:00:13
-                   real addition 1M 00:00:27
-          integer multiplication 1M 00:00:35
-             real multiplication 1M 00:00:43
-                integer division 1M 00:01:05
-                   real division 1M 00:00:51
-                 string indexing 1M 00:00:36
-                string iteration 1M 00:00:20
-                  new/dispose 1k 1M 00:00:23
-                new/dispose 128k 1M 00:00:23
-                  array copy 1k 10K 00:00:03
-                 array copy 128k 1K 00:00:48
-                          exp() 10K 00:00:28
-                          cos() 10K 00:00:04
--- a/examples/fastfire.inc
+++ b/examples/fastfire.inc
@ -1,5 +0,0 @@
-const FIREWIDTH = 319; FIREHEIGHT = 79; (* keep in sync with fastfire.s! *)
-type FireBuf = array [0..FIREHEIGHT, 0..FIREWIDTH] of integer;
-
-procedure FastFireUpdate(var f:FireBuf); external;
-procedure FastFireDraw(var f:FireBuf;screenx, screeny:integer); external;
--- a/examples/fastfire.s
+++ b/examples/fastfire.s
@ -1,326 +0,0 @@
-	; width and height of the fire cell matrix
-	; Be sure to sync this with fastfire.inc!
-	.EQU FIREWIDTH 319
-	.EQU FIREHEIGHT 79
-
-	;
-	; The cell matrix actually has one column
-	; and one row more than FIREWIDTH and
-	; FIREHEIGHT to handle the negative
-	; X offsets when calculating new
-	; cell values.
-	; Likewise, there is one more row.
-	; So rows are processed from 0 to FIREHEIGHT - 2
-	; and columms from 1 to FIREWIDTH - 1.
-
-	; cells considered for calculating new
-	; value for cell O (reference cells):
-	;	.....O......
-	;	....123.....
-	;	.....4......
-
-; args: pointer to fire cell buffer
-	.EQU FF_ROW_COUNT 0
-	.EQU FF_COL_COUNT 4
-	.EQU FF_ROW_OFFS 8
-	.EQU FF_OFFS1 12
-	.EQU FF_OFFS2 16
-	.EQU FF_OFFS3 20
-	.EQU FF_OFFS4 24
-	.EQU FF_CELL_PTR 28
-	.EQU FF_FS 32
-FASTFIREUPDATE:
-	FPADJ -FF_FS
-	STORE FF_CELL_PTR
-	LOADC FIREHEIGHT-1
-	STORE FF_ROW_COUNT
-
-	; calculate offsets for reference cells
-	LOADC FIREWIDTH+1
-	SHL 2
-	DUP
-	STORE FF_ROW_OFFS	; offset to next row: WIDTH*4
-	DEC 4			; offset to cell 1: row offset - 4
-	DUP
-	STORE FF_OFFS1
-	INC 4
-	DUP
-	STORE FF_OFFS2		; offset to cell 2: + 4
-	INC 4
-	STORE FF_OFFS3		; offset to cell 3: + 4
-	LOAD FF_ROW_OFFS
-	SHL 1			; offset to cell 4: row offset * 2
-	STORE FF_OFFS4
-
-	; start at column 1
-	LOAD FF_CELL_PTR
-	INC 4
-	STORE FF_CELL_PTR
-FF_ROW:
-	LOADC FIREWIDTH-1
-	STORE FF_COL_COUNT
-	
-FF_COL:
-	LOAD FF_CELL_PTR
-	LOAD FF_OFFS1
-	ADD
-	LOADI
-
-	LOAD FF_CELL_PTR
-	LOAD FF_OFFS2
-	ADD
-	LOADI
-
-	LOAD FF_CELL_PTR
-	LOAD FF_OFFS3
-	ADD
-	LOADI
-
-	LOAD FF_CELL_PTR
-	LOAD FF_OFFS4
-	ADD
-	LOADI
-
-	ADD
-	ADD
-	ADD
-
-	SHR
-	SHR
-
-	; if new cell value > 0, subtract 1 to cool down
-	DUP
-	CBRANCH.Z FF_SKIP
-	DEC 1
-FF_SKIP:
-	LOAD FF_CELL_PTR	; load cell ptr
-	SWAP			; swap with new value
-	STOREI 4		; store with postincrement
-	STORE FF_CELL_PTR	; save new ptr value
-
-	LOAD FF_COL_COUNT	; decrement column count
-	DEC 1
-	DUP
-	STORE FF_COL_COUNT
-	CBRANCH.NZ FF_COL	; loop if col count <> 0
-
-	; at the end of a row, go to next row
-	; by adding 8 to the cell pointer,
-	; skipping the first cell of the next row
-	LOAD FF_CELL_PTR
-	INC 8
-	STORE FF_CELL_PTR
-
-	LOAD FF_ROW_COUNT	; decrement row count
-	DEC 1
-	DUP
-	STORE FF_ROW_COUNT
-	CBRANCH.NZ FF_ROW	; loop if row count <> 0
-
-FF_EXIT:
-	FPADJ FF_FS
-	RET
-
-; framebuffer controller registers
-	.EQU FB_RA $900
-	.EQU FB_WA $901
-	.EQU FB_IO $902
-	.EQU FB_PS $903
-	.EQU FB_PD $904
-	.EQU FB_CTL $905
-	.EQU WORDS_PER_LINE 80
-
-; fire width in vmem words (strict left-to-right evaluation)
-	.EQU FFD_ROW_WORDS 1 + FIREWIDTH / 8
-
-; draw all fire cells
-; args: pointer to fire cell buffer, screen x, screen y
-	.EQU FFD_CELL_PTR 0
-	.EQU FFD_X 4
-	.EQU FFD_Y 8
-	.EQU FFD_ROW_COUNT 12
-	.EQU FFD_ROW_WORDCOUNT 16
-	.EQU FFD_VMEM_PTR 20
-	.EQU FFD_FS 24
-FASTFIREDRAW:
-	FPADJ -FFD_FS
-	STORE FFD_Y
-	STORE FFD_X
-	STORE FFD_CELL_PTR
-
-	; calculate video memory addr
-	; addr = y * 80 + X / 8
-	LOAD FFD_Y
-	SHL 2	; y * 16
-	SHL 2
-	DUP
-	SHL 2	; + y * 64
-	ADD	; = y * 80
-
-	LOAD FFD_X
-	SHR
-	SHR
-	SHR
-	ADD	; + x / 8
-
-	DUP
-	STORE FFD_VMEM_PTR
-	LOADC FB_WA	; set vmem write address
-	SWAP
-	STOREI
-	DROP
-
-	LOADC FIREHEIGHT + 1
-	STORE FFD_ROW_COUNT
-FFD_ROW:
-	LOADC FFD_ROW_WORDS
-	STORE FFD_ROW_WORDCOUNT
-
-	LOADC FB_WA	; set vmem write address
-	LOAD FFD_VMEM_PTR
-	STOREI
-	DROP
-
-FFD_WORD:
-	LOAD FFD_CELL_PTR	; load cell ptr
-	LOADC 0			; vmem word, start with 0
-
-	; leftmost pixel (0)
-	OVER	;			[ cptr, vmemw, cptr ]
-	LOADI	; load cell value	[ cptr, vmemw, cellval ]
-	SHR	; scale it down (from 7 bits to 4)
-	SHR
-	SHR	;			[ cptr, vmemw, cellval shr 3 ]
-	OR	;			[ cptr, vmemw ]
-	SWAP	;			[ vmemw, cptr ] 
-	INC 4	; increment cell ptr on stack [ vmemw, cptr + 4 ]
-	SWAP	;			[ cptr + 4, vmemw ]
-
-	SHL 2			; move bits to left for next pixel
-	SHL 2
-
-	; pixel 1
-	OVER
-	LOADI	; load cell value
-	SHR	; scale it down (from 7 bits to 4)
-	SHR
-	SHR
-	OR
-	SWAP
-	INC 4	; increment cell ptr on stack
-	SWAP
-
-	SHL 2			; move bits to left for next pixel
-	SHL 2
-
-	; pixel 2
-	OVER
-	LOADI	; load cell value
-	SHR	; scale it down (from 7 bits to 4)
-	SHR
-	SHR
-	OR
-	SWAP
-	INC 4	; increment cell ptr on stack
-	SWAP
-
-	SHL 2			; move bits to left for next pixel
-	SHL 2
-
-	; pixel 3
-	OVER
-	LOADI	; load cell value
-	SHR	; scale it down (from 7 bits to 4)
-	SHR
-	SHR
-	OR
-	SWAP
-	INC 4	; increment cell ptr on stack
-	SWAP
-
-	SHL 2			; move bits to left for next pixel
-	SHL 2
-
-	; pixel 4
-	OVER
-	LOADI	; load cell value
-	SHR	; scale it down (from 7 bits to 4)
-	SHR
-	SHR
-	OR
-	SWAP
-	INC 4	; increment cell ptr on stack
-	SWAP
-
-	SHL 2			; move bits to left for next pixel
-	SHL 2
-
-	; pixel 5
-	OVER
-	LOADI	; load cell value
-	SHR	; scale it down (from 7 bits to 4)
-	SHR
-	SHR
-	OR
-	SWAP
-	INC 4	; increment cell ptr on stack
-	SWAP
-
-	SHL 2			; move bits to left for next pixel
-	SHL 2
-
-	; pixel 6
-	OVER
-	LOADI	; load cell value
-	SHR	; scale it down (from 7 bits to 4)
-	SHR
-	SHR
-	OR
-	SWAP
-	INC 4	; increment cell ptr on stack
-	SWAP
-
-	SHL 2			; move bits to left for next pixel
-	SHL 2
-
-	; pixel 7
-	OVER
-	LOADI	; load cell value
-	SHR	; scale it down (from 7 bits to 4)
-	SHR
-	SHR
-	OR
-	SWAP
-	INC 4	; increment cell ptr on stack
-	SWAP
-
-	; store word to vmem
-	; vmem write addr will autoincrement
-	LOADC FB_IO
-	SWAP
-	STOREI
-	DROP
-
-	STORE FFD_CELL_PTR
-
-	; prepare for next word
-	LOAD FFD_ROW_WORDCOUNT
-	DEC 1
-	DUP
-	STORE FFD_ROW_WORDCOUNT
-	CBRANCH.NZ FFD_WORD
-
-	; prepare for next row
-	LOAD FFD_VMEM_PTR
-	LOADC WORDS_PER_LINE
-	ADD
-	STORE FFD_VMEM_PTR	
-
-	LOAD FFD_ROW_COUNT
-	DEC 1
-	DUP
-	STORE FFD_ROW_COUNT
-	CBRANCH.NZ FFD_ROW		
-FFD_EXIT:
-	FPADJ FFD_FS
-	RET
--- a/examples/fire.pas
+++ b/examples/fire.pas
@ -1,76 +0,0 @@
-{$H1}
-{$S2}
-program fire;
-const MAXX = 30;
-      MAXY = 50;
-var firebuf: array [0..MAXY, 0..MAXX] of integer;
-
-    firepalette: array [0..15] of integer =
-    	( $FFA, $FF8, $FF4, $FF0, $FE0, $FD0, $FA0, $F90,
-    	  $F00, $E00, $D00, $A00, $800, $600, $300, $000);
-    x,y:integer;
-
-procedure createPalette;
-var i:integer;
-begin
-	for i := 15 downto 0 do
-		setpalette(15 - i, firepalette[i]);
-end;
-
-procedure fireItUp;
-var x,y:integer;
-begin
-	y := MAXY - 1;
-	for x := 1 to MAXX - 1 do
-		firebuf[y, x] := random and 127;
-end;
-
-procedure updateFire;
-var i,x,y:integer;
-begin
-	for y := 0 to MAXY - 2 do
-		for x := 1 to MAXX - 1 do
-		begin
-			i :=
-				((firebuf[y + 1, x - 1]
-				+ firebuf[y + 1, x]
-				+ firebuf[y + 1, x + 1]
-				+ firebuf[y + 2, x])
-				) shr 2;
-			if i > 0 then
-				i := i - 1;
-			firebuf[y, x] := i;
-		end;
-end;
-
-procedure drawFire;
-var x, y, col:integer;
-begin
-	for y := 0 to MAXY - 1 do
-	begin
-		x := 0;
-		for col in firebuf[y] do
-		begin
-			putpixel(300 + x, 150 + y, col shr 3);
-			x := x + 1;
-		end;
-	end;
-end;
-
-begin
-	randomize;
-	initgraphics;
-	createPalette;
-	while not conavail do
-	begin
-		fireItUp;
-		updateFire;
-		drawFire;
-	end;
-
-	for y := 0 to MAXY do
-	begin
-		x := firebuf[y, 10];
-		drawline(0, y, x, y, 1);
-	end;
-end.
--- a/examples/fire2.pas
+++ b/examples/fire2.pas
@ -1,84 +0,0 @@
-{$H1}
-{$S1}
-program fire2;
-uses fastfire;
-
-const MAXX = FIREWIDTH;
-      MAXY = FIREHEIGHT;
-
-var firecells: FireBuf;
-
-    firepalette: array [0..15] of integer =
-    	{ ( $FFA, $FF8, $FF4, $FF0, $FE0, $FD0, $FA0, $F90,
-    	  $F00, $E00, $D00, $A00, $800, $600, $300, $000); }
-    	( $FFA, $FFA, $FFA, $FFA, $FF0, $FF0, $FF0, $FF0,
-    	  $FF0, $FD0, $FA0, $C00, $A00, $700, $400, $000);
-    x,y:integer;
-
-procedure createPalette;
-var i:integer;
-begin
-	for i := 15 downto 0 do
-		setpalette(15 - i, firepalette[i]);
-end;
-
-procedure fireItUp;
-var x,y:integer;
-begin
-	y := MAXY - 1;
-	for x := 1 to MAXX - 1 do
-		firecells[y, x] := random and 127;
-end;
-
-
-procedure updateFire;
-var i,x,y:integer;
-begin
-	for y := 0 to MAXY - 2 do
-		for x := 1 to MAXX - 1 do
-		begin
-			i :=
-				((firecells[y + 1, x - 1]
-				+ firecells[y + 1, x]
-				+ firecells[y + 1, x + 1]
-				+ firecells[y + 2, x])
-				) shr 2;
-			if i > 0 then
-				i := i - 1;
-			firecells[y, x] := i;
-		end;
-end;
-
-procedure drawFire;
-var x, y, col:integer;
-begin
-	for y := 0 to MAXY - 1 do
-	begin
-		x := 0;
-		for col in firecells[y] do
-		begin
-			putpixel(100 + x, 150 + y, col shr 3);
-			x := x + 1;
-		end;
-	end;
-end;
-
-begin
-	randomize;
-	initgraphics;
-	createPalette;
-	while not conavail do
-	begin
-		fireItUp;
-		FastFireUpdate(firecells);
-		{ updateFire; }
-		FastFireDraw(firecells, 160, 100);
-		{ drawFire; }
-	end;
-
-	for y := 0 to MAXY do
-	begin
-		x := firecells[y, 10];
-		drawline(0, y, x, y, 1);
-	end;
-end.
--- a/examples/grey.pict
+++ b/examples/grey.pict
--- a/examples/pcmtest.pas
+++ b/examples/pcmtest.pas
@ -1,47 +0,0 @@
-{$H1536}
-program pcmtest;
-uses pcmaudio;
-
-var filename:string;
-    buf:SndBufPtr;
-    f:file;
-    size:integer;
-    i:integer;
-    c:char;
-    sampleRate:integer;
-    err:integer;
-begin
-	if ParamCount > 0 then
-		filename := ParamStr(1)
-	else
-	begin
-		write('Filename> ');
-		readln(filename);
-	end;
-
-	err := 1;
-	if ParamCount > 1 then
-		val(ParamStr(2),sampleRate, err);
-
-	if err <> 0 then
-		sampleRate := 16000;
-
-	open(f, filename, ModeReadOnly);
-	size := FileSize(f);
-	new(buf, size);
-
-	buf^ := '';
-	write('Reading ', size, ' bytes...');
-	for i := 1 to size do
-	begin
-		read(f,c);
-		AppendChar(buf^,c);
-	end;
-	writeln;
-
-	close(f);
-
-	PlaySample(buf, sampleRate);
-
-	dispose(buf);
-end.
--- a/examples/pcmtest2.pas
+++ b/examples/pcmtest2.pas
@ -1,74 +0,0 @@
-{$H2560}
-program pcmtest2;
-uses pcmaudio;
-
-var filename:string;
-    buf:SndBufPtr;
-    sampleRate:integer;
-    err:integer;
-    done:boolean;
-    c:char;
-
-function readAudioFile(fname:string):SndBufPtr;
-var i,size:integer;
-    c:char;
-    buf:SndBufPtr;
-    f:file;
-begin
-	open(f, fname, ModeReadOnly);
-	size := FileSize(f);
-	new(buf, size);
-
-	buf^ := '';
-	write('Reading ', size, ' bytes...');
-	for i := 1 to size do
-	begin
-		read(f,c);
-		AppendChar(buf^,c);
-	end;
-	writeln;
-
-	close(f);
-
-	readAudioFile := buf;
-end;
-
-begin
-	if ParamCount > 0 then
-		filename := ParamStr(1)
-	else
-	begin
-		write('Filename> ');
-		readln(filename);
-	end;
-
-	err := 1;
-	if ParamCount > 1 then
-		val(ParamStr(2), sampleRate, err);
-	if err > 0 then
-		sampleRate := 32000;
-
-	buf := readAudioFile(filename);
-
-	SampleQStart(buf, sampleRate);
-
-	write('Press ESC to stop> ');
-	done := false;
-	while not done do
-	begin
-		read(c);
-		if c = #27 then
-		begin
-			done := true; writeln(';');
-		end
-		else
-		if c = '?' then
-		begin
-			writeln; writeln('Queue: ', SampleQSize);
-		end;
-	end;
-
-	SampleQStop;
-
-	dispose(buf);
-end.
--- a/examples/rocket.sprt
+++ b/examples/rocket.sprt
--- a/examples/shinkansen.pict
+++ b/examples/shinkansen.pict
--- a/examples/snow_leopard.pict
+++ b/examples/snow_leopard.pict
--- a/examples/sprites.inc
+++ b/examples/sprites.inc
@ -1,4 +1,4 @@
-type SpritePixels = array[0..128] of integer;
+type SpritePixels = array[0..31] of integer;
 type BackgroundPixels = array[0..31999] of integer;

 procedure PutSprite(x,y:integer; var sprite: SpritePixels); external;
--- a/examples/sprites.s
+++ b/examples/sprites.s
@ -1,5 +1,4 @@
-	.EQU SPRITE_HEIGHT 32	; height in lines
-	.EQU SPRITE_STRIPES 4	; width in words i.e. 8-pixel stripes
+	.EQU SPRITE_HEIGHT 16

        .EQU WORDS_PER_LINE 80
        .EQU FB_RA      $900
@ -66,8 +65,7 @@ CALC_VMEM_ADDR:
 	.EQU PS_Y		16
 	.EQU PS_SHIFT_C		20
 	.EQU PS_SPILL		24
-	.EQU PS_STRIPE_C	28
-	.EQU PS_FS 32
+	.EQU PS_FS 28
 PUTSPRITE:
 	FPADJ -PS_FS
 	STORE PS_SPRITE_DATA
@ -162,14 +160,10 @@ PS_LOOP2_X:
 	STOREI			; store result into i/o reg
 	DROP

-	; set counter for remaining stripes
-	LOADC SPRITE_STRIPES - 1
-	STORE PS_STRIPE_C
+	;
+	; process spilled bits and right half of sprite data
+	;

-	;
-	; process spilled bits and next vertical stripe of sprite data
-	;
-PS_NEXT_STRIPE:
 	; put spill bits on stack for later
 	LOAD PS_SPILL

@ -182,9 +176,7 @@ PS_NEXT_STRIPE:
 	; reset spill bits
 	LOADC 0
 	STORE PS_SPILL
-
-	; last spill bits are on ToS now
-
+	
 	; shift pixel data to right
 	LOAD PS_SHIFT_C		; load shift count
 PS_LOOP3:			; test it for zero
@ -238,14 +230,8 @@ PS_LOOP3_X:
 	SWAP
 	STOREI
 	DROP
-
-	LOAD PS_STRIPE_C	; decrement stripe count
-	DEC 1
-	DUP
-	STORE PS_STRIPE_C
-	CBRANCH.NZ PS_NEXT_STRIPE ; if non-zero, next stripe
-
-	; write spilled bits of the last stripe into next vmem word
+	
+	; write spilled bits into next vmem word
 	LOAD PS_SPILL		; get spill bits
 	DUP
 	LOADCP CALC_MASK	; calculate sprite mask for spill bits
@ -288,8 +274,7 @@ PS_L_XT:
 	.EQU UD_S_BGDATA 12
 	.EQU UD_S_OFFSET 16
 	.EQU UD_S_BGORIG 20
-	.EQU UD_STRIPE_C 24
-	.EQU UD_S_FS 28
+	.EQU UD_S_FS 24
 UNDRAWSPRITE:
 	FPADJ -UD_S_FS
 	STORE UD_S_BGORIG
@ -333,35 +318,25 @@ UD_S_L1:
 	STOREI
 	; reuse addr from STOREI

-	LOADC SPRITE_STRIPES - 1 ; set remaining stripe count
-	STORE UD_STRIPE_C
-
-UD_NEXT_STRIPE:
-	; load next word of background data	
+	; load 2nd word of background data	
 	LOAD UD_S_BGDATA
 	INC 4
 	DUP
 	STORE UD_S_BGDATA
 	LOADI
 	STOREI ; and write it to vmem
-	; reuse addr from STOREI
+	DROP

-	LOAD UD_STRIPE_C	; decrease remaining stripe count
-	DEC 1
-	DUP
-	STORE UD_STRIPE_C
-	CBRANCH.NZ UD_NEXT_STRIPE ; if non-zero, next stripe
-
-	DROP ; remove addr from STOREI
-
-	; if pixel shift is zero, no spill word
+	; if pixel shift is zero, no 3rd word
 	LOAD UD_S_PXS
 	CBRANCH.Z UD_S_L2

-	; load next word of background data
+	; load 3rd word of background data
 	LOADCP FB_IO
 	LOAD UD_S_BGDATA
 	INC 4
+	DUP
+	STORE UD_S_BGDATA
 	LOADI
 	STOREI ; and write it to vmem
 	DROP
--- a/examples/walking.sprt
+++ b/examples/walking.sprt
--- a/examples/xmas.pas
+++ b/examples/xmas.pas
@ -1,7 +1,3 @@
-(* This program does not work anymore, because
-   it uses the old sprite routines with 16x16 sprites.
-   It is only included for historical reasons.
-   *)
 program XmasAnimation;
 uses sprites;

--- a/lib/corelib.s
+++ b/lib/corelib.s
@ -612,9 +612,6 @@ WAIT1LOOP:
 ; length must be multiple of wordsize.
 ; if it is not, the last (partial) word is not cleared.
 _CLEARMEM:
-	OVER	; check for null pointer
-	CBRANCH.Z CLEARMEM_X
-
 	SHR
 	SHR	; calculate length in words

--- a/lib/pcmaudio.inc
+++ b/lib/pcmaudio.inc
@ -1,7 +0,0 @@
-type SndBuf = string[32768];
-type SndBufPtr = ^SndBuf;
-
-procedure PlaySample(buf:SndBufPtr;sampleRate:integer); external;
-procedure SampleQStart(buf:SndBufPtr;sampleRate:integer); external;
-procedure SampleQStop; external;
-function SampleQSize:integer; external;
--- a/lib/pcmaudio.s
+++ b/lib/pcmaudio.s
@ -1,247 +0,0 @@
-	.EQU AUDIO_BASE $A00
-	.EQU IRQC_REG $980
-	.EQU IRQC_EN $80
-
-; args: sample rate
-START_PCMAUDIO:
-	; calculate clock divider
-	LOADCP 77000000
-	SWAP
-	LOADCP _DIV
-	CALL
-
-	LOADC AUDIO_BASE + 1
-	SWAP		; put clock divider on ToS
-;	LOADCP 4812	; clock divider for 16KHz sample rate
-;	LOADCP 2406	; clock divider for 32KHz sample rate
-	STOREI 1
-	LOADCP 32768	; set amplitude to biased 0
-	STOREI
-	DROP
-	LOADC AUDIO_BASE
-	LOADC 17	; enable channel, enable interrupt
-	STOREI
-	DROP
-	RET
-
-STOP_AUDIO:
-	LOADC AUDIO_BASE
-	LOADC 0
-	STOREI
-	DROP
-	RET
-
-; args: pointer to pascal string, sample rate
-	.EQU PS_PTR 0
-	.EQU PS_COUNT 4
-	.EQU PS_FS 12
-PLAYSAMPLE:
-	FPADJ -PS_FS
-
-	LOADCP START_PCMAUDIO
-	CALL
-
-	DUP
-	LOADI		; get string size from header
-	SHR		; divide by 4 to get word count
-	SHR
-
-	STORE PS_COUNT
-	INC 8		; skip rest of header
-	STORE PS_PTR	; store sample data pointer
-
-PS_L0:
-	LOAD PS_PTR	; load pointer
-	INC.S1.X2Y 4	; increment and keep old value
-	STORE PS_PTR	; store incremented value
-
-	LOADI		; load 32 bit word
-	DUP
-	BROT		; get upper 16 bit word
-	BROT
-	LOADCP $FFFF
-	AND
-
-	LOADCP PLAY_1SAMPLE
-	CALL
-
-	LOADCP $FFFF	; get lower 16 bit word
-	AND
-	LOADCP PLAY_1SAMPLE
-	CALL
-
-	LOAD PS_COUNT	; load word count
-	DEC 1		; decrement
-	DUP
-	STORE PS_COUNT
-	CBRANCH.NZ PS_L0 ; loop if not zero
-
-	LOADCP STOP_AUDIO
-	CALL
-
-	FPADJ PS_FS
-	RET
-
-; play one sample, waiting
-; for the clock divider, which
-; is visible via the phase flag
-; args: 16-bit unsigned sample
-PLAY_1SAMPLE:
-
-PLAY1_L0:
-	LOADC AUDIO_BASE
-	LOADI
-	LOADC 8		; get fifo_full flag
-	AND
-	CBRANCH.NZ PLAY1_L0 ; loop if fifo is full
-
-	LOADC AUDIO_BASE+2 ; store amplitude value
-	SWAP
-	STOREI
-	DROP
-	RET
-
-; start interrupt-driven sample playback
-; args: pointer to pascal string, sample rate
-SAMPLEQSTART:
-	LOADCP START_PCMAUDIO
-	CALL
-
-	LOADCP SMPLQ_COUNT
-	OVER
-	LOADI		; get string size from header
-	SHR		; divide by 4 to get word count
-	SHR
-
-	STOREI
-	DROP
-
-	LOADCP SMPLQ_PTR
-	SWAP
-	INC 8		; skip rest of header
-	STOREI		; store sample data pointer
-	DROP
-
-	LOADCP SMPLQ_ISR ; set interrupt handler
-	STOREREG IV
-
-	LOADC IRQC_REG	; enable irq
-	LOADC IRQC_EN
-	STOREI
-	DROP
-
-	RET
-
-SAMPLEQSTOP:
-	LOADCP SMPLQ_PTR
-	LOADC 0
-	STOREI
-	DROP
-
-	LOADCP STOP_AUDIO
-	CALL
-
-	LOADC IRQC_REG	; disable irq
-	LOADC 0
-	STOREI
-	DROP
-	RET
-
-SAMPLEQSIZE:
-	LOADCP SMPLQ_COUNT
-	LOADI
-	RET
-
-SMPLQ_PTR: .WORD 0
-SMPLQ_COUNT: .WORD 0
-
-SMPLQ_ISR:
-	LOADC IRQC_REG
-	LOADI
-	LOADC 4	; check for audio interrupt
-	AND
-	CBRANCH.Z SMPLQ_I_XT ; if flag not set, exit
-
-SMPLQ_I_L:
-	LOADCP SMPLQ_PTR
-	LOADI			; load word pointer
-	DUP
-	CBRANCH.NZ SMPLQ_I_B	; check for null pointer
-	DROP
-	BRANCH SMPLQ_I_XT	; if null, end interrupt routine
-SMPLQ_I_B:
-	LOADI	; load next word
-	DUP
-
-	BROT	; get high half-word
-	BROT
-	LOADCP $FFFF
-	AND
-
-	LOADC AUDIO_BASE+2
-	SWAP
-	STOREI	; write sample, keep addr
-
-	SWAP	; addr to NoS, lower halfword on ToS
-	LOADCP $FFFF
-	AND
-	STOREI	; write sample
-	DROP
-
-	; decrement word count
-	LOADCP SMPLQ_COUNT
-	LOADI.S1.X2Y		; load counter, keep addr
-	DEC 1
-	DUP
-	CBRANCH.Z SMPLQ_I_END	; end if zero
-
-	STOREI			; store new counter value
-	DROP
-
-	; increment pointer
-	LOADCP SMPLQ_PTR
-	LOADI.S1.X2Y
-	INC 4
-	STOREI
-	DROP
-
-	; check if fifo is full
-	LOADC AUDIO_BASE
-	LOADI
-	LOADC 8	; fifo_full
-	AND
-	CBRANCH.Z SMPLQ_I_L ; next sample if not full
-
-	LOADC AUDIO_BASE
-	LOADC 17	; re-enable channel interrupt
-	STOREI
-	DROP
-
-	BRANCH SMPLQ_I_XT
-
-	; end playback, set ptr and counter to zero
-SMPLQ_I_END:
-	DROP
-	DROP
-	LOADCP SMPLQ_PTR
-	LOADC 0
-	STOREI
-	DROP
-	LOADCP SMPLQ_COUNT
-	LOADC 0
-	STOREI
-	DROP
-
-	; set amplitude out to zero (biased)
-	LOADC AUDIO_BASE+2
-	LOADCP 32768
-	STOREI
-	DROP
-
-SMPLQ_I_XT:
-	LOADC IRQC_REG		; re-enable interrupts
-	LOADC IRQC_EN
-	STOREI
-	DROP
-	LOADREG IR		; jump via interrupt return register
-	JUMP
--- a/lib/runtime.s
+++ b/lib/runtime.s
@ -1764,34 +1764,6 @@ MEM_DUMP_L0:
 	DROP
 	RET

-; calculate total free heap space
-; args: none
-; returns: cumulative size of all free chunks in bytes
-MEMAVAIL:
-	FPADJ -4
-	LOADC 0
-	STORE 0	; start with zero as result
-
-	LOADCP _HEAP_ANCHOR
-MAV_L:
-	DUP	; dup chunk ptr for later
-	INC 4	; move to size field
-	LOADI	; load chunk size
-	LOAD 0  ; add to current result value
-	ADD
-	STORE 0
-
-	LOADI	; load next ptr
-	DUP
-	LOADCP _HEAP_ANCHOR ; compare with anchor
-	CMPU NE
-	CBRANCH MAV_L       ; if not equal, loop
-MAX_XT:
-	DROP	; drop chunk ptr
-	LOAD 0	; put result value on stack
-	FPADJ 4
-	RET
-
 ; check if a pointer is part of the free list
 ; args: pointer returned by MEM_ALLOC
 ; throws runtime error if the pointer is found
@ -1931,12 +1903,6 @@ _CLEARESTACK_XT:
 ; Terminate program: clear estack and
 ; jump to coreloader
 PTERM:
-	; just to be safe, disable interrupts
-	LOADC $980
-	LOADC 0
-	STOREI
-	DROP
-
 	LOADCP _CLEARESTACK
 	CALL
 	LOADCP LOADER_START
--- a/lib/sdcardlib.s
+++ b/lib/sdcardlib.s
@ -264,8 +264,8 @@ CARD_OK:
 ; set fast transfer rate
 CARDFASTCLK:
 	LOADC SPIREG
-	; set clock divider to ~2.75MHz
-	LOADCP SPI_CLK_DIV_WR,7 ; using the LOADCP with offset syntax here
+	; set clock divider to ~2,6MHz
+	LOADCP SPI_CLK_DIV_WR,10 ; using the LOADCP with offset syntax here
 	STOREI
 	DROP
 	RET
--- a/lib/stdlib.inc
+++ b/lib/stdlib.inc
@ -18,9 +18,8 @@ const IONoError 	=  0;
      IOReadOnly 	=  8;
      IOInvalidOp	=  9;
      IOInvalidFormat   = 10;
-      IONoMem		= 11;
-      IOUserIntr	= 12;
-      IOMaxErr          = 12;
+      IOUserIntr	= 11;
+      IOMaxErr          = 11;

 const PArgMax = 7;

@ -149,7 +148,6 @@ procedure appendchar(var s:string; aChar:char); external;
 procedure strmoveup(var s:string;index,length,delta:integer); external;
 procedure strmovedown(var s:string;index,length,delta:integer); external;
 procedure RuntimeError(var s:string); external;
-function MemAvail:integer; external;

 (* from stdlib *)
 function copy(s:string[256];index,count:integer):string[256]; external;
@ -207,7 +205,7 @@ procedure readvolumeblks(volumeid:integer; destbuf:^iobuffer; blkno:integer; blk
 procedure writevolumeblks(volumeid:integer; srcbuf:^iobuffer; blkno:integer; blkCount: integer; var error:integer);
 	external;
 function findvolume(name:string):integer; external;
-procedure openvolumeid(volid:integer;var error:integer); external;
+procedure openvolumeid(volid:integer); external;
 procedure closevolumeid(volid:integer); external;
 function IOResult(var fil:file):integer; external;
 function ErrorStr(err:integer):string; external;
--- a/lib/stdlib.pas
+++ b/lib/stdlib.pas
@ -26,9 +26,8 @@ const IONoError 	=  0;
      IOReadOnly 	=  8;
      IOInvalidOp	=  9;
      IOInvalidFormat   = 10;
-      IONoMem		= 11;
-      IOUserIntr	= 12;
-      IOMaxErr          = 12;
+      IOUserIntr	= 11;
+      IOMaxErr          = 11;

 const PArgMax = 7;

@ -134,7 +133,7 @@ var DefaultVolumeId:integer;
 		character to the runtime error routine
 		which takes null-terminated strings.
 	*)
-var ioerrordesc: array [0..IOMaxErr] of string[20] = (
+var ioerrordesc: array [0..11] of string[20] = (
 	'No error',
        'File not found',
 	'Volume not found',
@ -146,7 +145,6 @@ var ioerrordesc: array [0..IOMaxErr] of string[20] = (
 	'File is readonly',
 	'Invalid operation',
 	'Invalid format',
-	'Not enough memory',
 	'Interrupted by user'
 	);

@ -1185,17 +1183,7 @@ ext:
 		code := 0;
 	end
 	else
-	begin
-		if i = 1 then  (* empty string gives error position 1 *)
-			code := 1
-		else
-			code := i - 1;
-	end;
-end;
-
-procedure errorhalt(var fil:file);
-begin
-	RuntimeError(ioerrordesc[fil.lastError]);
+		code := i - 1;
 end;

 procedure checkerror(var fil:file);
@ -1203,7 +1191,7 @@ begin
 	if fil.lastError <> 0 then
 	begin
 		if not fil.errorAck then
-			errorhalt(fil)
+			RuntimeError(ioerrordesc[fil.lastError])
 		else
 		begin
 			fil.lastError := 0;
@ -1346,16 +1334,12 @@ procedure freadreal(var v:real;var f:file);
 var buf:string[40];
    errpos:integer;
 begin
-	errpos := -1;
 	fskipwhite(f);
 	fscanbuf(f,ScanReal, buf);
 	if f.lastError = 0 then
 		val(buf, v, errpos);
 	if errpos <> 0 then
-	begin
 		fileerror(f, IOInvalidFormat);
-		checkerror(f);
-	end;
 end;

 procedure freadstring(var s:string; var f:file);
@ -1556,17 +1540,13 @@ begin
 	end;
 end;

-procedure openvolumeid(volid:integer;var error:integer);
+procedure openvolumeid(volid:integer);
 begin
-	error := 0;
 	with volumeTable[volid] do
 	begin
 		if dirCache = nil then
-			newOrNil(dirCache);
-		if dirCache <> nil then
-			openFilesCount := openFilesCount + 1
-		else
-			error := IONoMem;
+			new(dirCache);
+		openFilesCount := openFilesCount + 1;
 	end;
 end;

@ -1685,21 +1665,12 @@ begin
 	{ writeln('  readbuf data: ', fil.buffer^[0][0]); }
 end;

-procedure close(var aFile:file); forward;
-
-(* Set error state on file and close it.
-   Buffer will not be flushed as that might
-   have caused the error.
-*)
 procedure fileerror(var fil:file; error:integer);
 begin
+	(* should check if there was an error already
+	   and throw a runtime error in that case *)
 	fil.lastError := error;
 	fil.errorAck := false;
-	if fil.buffer <> nil then
-	begin
-		fil.needsflush := false;
-		close(fil);
-	end;
 end;

 function IOResult(var fil:file):integer;
@ -1844,8 +1815,6 @@ end;

 function filesize(var fil:file):integer;
 begin
-	checkerror(fil);
-
 	if fil.typ = IOChannel then
 		filesize := -1
 	else
@ -2044,28 +2013,23 @@ begin

 	aFile.typ := IODiskFile;
 	aFile.mode := mode;
-	newOrNil(aFile.buffer);
-	if aFile.buffer = nil then
-		fileerror(aFile, IONoMem)
-	else
-	begin
-		aFile.bufpos := 0;
-		aFile.bufsize := DefaultBufSize;
-		aFile.needsflush := false;
-		aFile.changed := false;
-		aFile.lastError := 0;
-		aFile.errorAck := false;
-		aFile.volumeid := volid;
-		aFile.fileno := slotno;
-		aFile.filpos := 0;
-		aFile.bufStart := 1;
-		aFile.size := dirslot.sizeBytes;
-		aFile.sizeExtents := dirslot.sizeBytes div extentSize + 1;
-		aFile.bufBlocks := DefaultBufBlocks;
-		aFile.extentBlocks := extentSize div 512;
+	new(aFile.buffer);
+	aFile.bufpos := 0;
+	aFile.bufsize := DefaultBufSize;
+	aFile.needsflush := false;
+	aFile.changed := false;
+	aFile.lastError := 0;
+	aFile.errorAck := false;
+	aFile.volumeid := volid;
+	aFile.fileno := slotno;
+	aFile.filpos := 0;
+	aFile.bufStart := 1;
+	aFile.size := dirslot.sizeBytes;
+	aFile.sizeExtents := dirslot.sizeBytes div extentSize + 1;
+	aFile.bufBlocks := DefaultBufBlocks;
+	aFile.extentBlocks := extentSize div 512;

-		seek(aFile,0);
-	end;
+	seek(aFile,0);
 end;

 procedure updatedirslot(var aFile:file);
@ -2088,22 +2052,19 @@ procedure close(var aFile:file);
 begin
 	if aFile.typ = IODiskFile then
 	begin
-		if aFile.lastError = IOFileClosed then
-			errorhalt(aFile);
 		{ writeln('close needsflush:', aFile.needsflush, ' changed:', aFile.changed, ' error:', aFile.lastError); }
 		if aFile.needsflush then
 			flushfile(aFile);
-
-		{ writeln('close f.buffer:', aFile.buffer); }
-		dispose(aFile.buffer);
-		aFile.buffer := nil;
-
 		if aFile.lastError = 0 then
 		begin
+			fileerror(aFile, IOFileClosed);
+			{ writeln('close f.buffer:', aFile.buffer); }
+			dispose(aFile.buffer);
+			aFile.buffer := nil;
+
 			if aFile.changed then
 				updatedirslot(aFile);
-			if aFile.lastError = 0 then
-				fileerror(aFile, IOFileClosed);
+
 		end;

 		closevolumeid(aFile.volumeid);
@ -2282,9 +2243,8 @@ begin

 	if volid > 0 then
 	begin
-		openvolumeid(volid, error);
-		if error = 0 then
-			slotno := findfile(volid, fname, dirs, error)
+		openvolumeid(volid);
+		slotno := findfile(volid, fname, dirs, error)
 	end
 	else
 		error := IOVolNotFound;
--- a/pcomp/Makefile
+++ b/pcomp/Makefile
@ -3,17 +3,12 @@ SASM=./sasm
 LSYMGEN=./lsymgen

 .SUFFIXES:
-.SUFFIXES: .pas .o .s .prog
-
-.pas.s:
-	$(PCOMP) $<
-.s.prog:
-	$(SASM) $<
+.SUFFIXES: .pas .o

 .pas:
 	fpc -Mobjfpc -gl $<

-all: pcomp sasm sdis lsymgen shortgen nativeprogs
+all: pcomp sasm sdis lsymgen shortgen

 libs: pcomp sasm lsymgen shortgen
 	$(SASM) ../lib/coreloader.s
@ -22,23 +17,31 @@ libs: pcomp sasm lsymgen shortgen
 	$(SASM) ../lib/stdlibwrap.s ../lib/stdlib.lib
 	$(LSYMGEN) ../lib/stdlibwrap.sym ../lib/stdlib.lsym

-test: sasm.s pcomp.s lsymgen.s shortgen.s
+nativecomp: pcomp sasm libs
+	$(PCOMP) sasm.pas
+	$(PCOMP) pcomp.pas
+	$(PCOMP) lsymgen.pas
+	$(PCOMP) shortgen.pas

-testprgs: sasm.prog pcomp.prog lsymgen.prog shortgen.prog
-
-nativecomp: libs pcomp.prog sasm.prog lsymgen.prog shortgen.prog
-
-nativeprogs: pcomp ../progs/shell.prog ../progs/editor.prog ../progs/reclaim.prog \
-        ../progs/dumpdir.prog ../progs/partmgr.prog ../progs/xfer.prog \
-        ../progs/recover.prog ../progs/changemem.prog
+nativeprogs: nativecomp
+	$(PCOMP) ../progs/shell.pas
+	$(PCOMP) ../progs/editor.pas
+	$(PCOMP) ../progs/reclaim.pas
+	$(PCOMP) ../progs/dumpdir.pas
+	$(PCOMP) ../progs/partmgr.pas
+	$(PCOMP) ../progs/xfer.pas
 	$(SASM) ../lib/rommon.s
 	$(SASM) -A ../lib/rommon.s ../lib/rom.mem

-examples: nativecomp ../tests/readtest.prog ../tests/readchartest.prog ../tests/timetest.prog \
-	../tests/test133.prog ../tests/cchangetest.prog ../tests/tree.prog
+examples: nativecomp
+	$(PCOMP) ../tests/readtest.pas
+	$(PCOMP) ../tests/readchartest.pas
+	$(PCOMP) ../tests/timetest.pas
+	$(PCOMP) ../tests/test133.pas
 	-$(PCOMP) ../examples/chase.pas
-	-$(SASM) ../examples/chase.s
+	$(PCOMP) ../tests/cchangetest.pas
+	$(PCOMP) ../tests/tree.pas
 	-$(MAKE) -C ../rogue -f Makefile.tridoracpu

 clean:
-	rm -f pcomp sasm sdis libgen lsymgen *.o *.s *.prog
+	rm -f pcomp sasm sdis libgen lsymgen *.o *.s
--- a/pcomp/emit.pas
+++ b/pcomp/emit.pas
@ -324,9 +324,7 @@ begin
 	rewindStringList(usedUnits);
 	while nextStringListItem(usedUnits, unitName) do
 		emitInclude(unitName + UnitSuffix2);
-	(* _END label needs to be word-aligned because
-		it is used as the start of the heap *)
-	emitIns('.ALIGN');
+
 	emitLabelRaw('_END');
 end;

--- a/pcomp/make.bat
+++ b/pcomp/make.bat
@ -27,8 +27,6 @@ py pcomp.py ..\progs\reclaim.pas
 py pcomp.py ..\progs\dumpdir.pas
 py pcomp.py ..\progs\partmgr.pas
 py pcomp.py ..\progs\xfer.pas
-py pcomp.py ..\progs\recover.pas
-py pcomp.py ..\progs\changemem.pas
 sasm ..\lib\rommon.s
 sasm -A ..\lib\rommon.s ..\lib\rom.mem

--- a/pcomp/pcomp.pas
+++ b/pcomp/pcomp.pas
@ -43,7 +43,7 @@ type 	TokenType = (
 		ArrayType, RecordType, PointerType, StringCharType, EnumType, 
 		SetType, UnresolvedType );

-	SpecialProc = ( NoSP, NewSP, New0SP, DisposeSP, ReadSP, WriteSP, ReadlnSP, WritelnSP,
+	SpecialProc = ( NoSP, NewSP, DisposeSP, ReadSP, WriteSP, ReadlnSP, WritelnSP,
 			SetlengthSP, ValSP, StrSP, ExitSP );
 	SpecialFunc = ( NoSF, TruncSF, FracSF, IntSF, SqrSF, SuccSF, PredSF,
 			OddSF, ChrSF, OrdSF, AbsSF);
@ -291,7 +291,7 @@ var
 		'UNIT', 'IMPLEMENTATION', 'INTERFACE', 'USES',
 		'_' );
 		specialprocnames: array [SpecialProc] of string[12] = (
-			'_', 'NEW', 'NEWORNIL', 'DISPOSE', 'READ', 'WRITE', 'READLN', 'WRITELN', 'SETLENGTH',
+			'_', 'NEW', 'DISPOSE', 'READ', 'WRITE', 'READLN', 'WRITELN', 'SETLENGTH',
 			'VAL','STR', 'EXIT');
 		specialfuncnames: array [SpecialFunc] of string[8] = (
 			'_', 'TRUNC', 'FRAC', 'INT', 'SQR', 'SUCC', 'PRED', 'ODD',
@ -4500,7 +4500,7 @@ begin
 	isFunction := aProc^.returnType.baseType <> NoType;
 end;

-procedure parseNew(checkNil:boolean);
+procedure parseNew;
 var memLoc: MemLocation;
    typeReturn: TypeSpec;
 begin
@ -4526,17 +4526,17 @@ begin
 		emitLoadConstantInt(memLoc.typ.pointedType^.size);
 		emitMemAlloc;

-		(*We need to call CLEARMEM when the allocated type
-			contains strings.
-			INITSTRING checks if the header is non-zero to see if
-			the string is already initialized, and the allocated
-			chunk might contain random data so it would look
-			like an initialized string. *)
 		if typeContainsString(memLoc.typ.pointedType^) then
 			emitClearAlloc(memLoc.typ.pointedType);
 	end;
-	if checkNil then
-		emitCheckAlloc;
+	emitCheckAlloc;
+
+	(*We need to call CLEARMEM when the allocated type
+		contains strings.
+		INITSTRING checks if the header is non-zero to see if
+		the string is already initialized, and the allocated
+		chunk might contain random data so it would look
+		like an initialized string. *)

 	writeVariable(memLoc);

@ -5017,9 +5017,7 @@ begin
 	NoSP:
 		errorExit2('internal error in parseSpecialProcCall', lastToken.tokenText);
 	NewSP:
-		parseNew(true);
-	New0SP:
-		parseNew(false);
+		parseNew;
 	DisposeSP:
 		parseDispose;
 	ReadSP:
--- a/pcomp/sasm.pas
+++ b/pcomp/sasm.pas
@ -1,7 +1,7 @@
 (* Copyright 2021-2024 Sebastian Lederer. See the file LICENSE.md for details *)
 {$MODE objfpc}
 {$H600}
-{$S32}
+{$S4}
 program sasm;
 {$!}{$ifdef FPC}uses math,crt;{$endif}
 {$R+}
@ -2056,9 +2056,6 @@ begin
 			operandValue := 0;
 		emitBlock(count, operandValue);
 	end
-	else
-	if lastToken.tokenText = '.ALIGN' then
-		alignOutput(wordSize)
 	else
 		errorExit2('Unrecognized directive', lastToken.tokenText);
 end;
--- a/progs/changemem.pas
+++ b/progs/changemem.pas
@ -1,173 +0,0 @@
-program changemem;
-const ProgramMagic = $00100AFE;
-type ProgramHeader = record
-		magic:integer;
-		heapSize:integer;
-		stackSize:integer;
-		mainPtr:integer;
-	end;
-
-var filename:string;
-    h:ProgramHeader;
-
-procedure showHex(value:integer);
-var i:integer;
-    digit:integer;
-    digits:array[1..8] of char;
-    ch:char;
-begin
-	for i := 1 to 8 do
-	begin
-		digit := value and 15;
-		value := value shr 4;
-
-		if digit < 10 then
-			ch := chr(digit + ord('0'))
-		else
-			ch := chr(digit - 10 + ord('A'));
-		digits[i] := ch;
-	end;
-	for i := 8 downto 1 do
-		write(digits[i]);
-end;
-
-procedure showValue(labl:string; value:integer);
-begin
-	write(labl:20, ' ');
-	write(value:8, ' (');
-	showHex(value);
-	writeln(')');
-end;
-
-procedure showHeader(var h:ProgramHeader);
-begin
-	showValue('heap size', h.heapSize);
-	showValue('stack size', h.stackSize);
-	showValue('main entry point', h.mainPtr);
-end;
-
-procedure readHeader(var filename:string;var h:ProgramHeader);
-var f:file;
-begin
-	writeln('reading file ', filename);
-	open(f, filename, ModeReadOnly);
-	if IOResult(f) <> 0 then
-	begin
-		writeln('Error opening file: ', ErrorStr(IOResult(f)));
-		halt;
-	end
-	else
-	begin
-		read(f, h);
-		if IOResult(f) <> 0 then
-		begin
-			writeln('Error reading header: ', ErrorStr(IOResult(f)));
-			halt;
-		end;
-		close(f);
-	end;
-end;
-
-procedure writeHeader(var filename:string;var h:ProgramHeader);
-var f:file;
-begin
-	writeln('writing file ', filename);
-	open(f, filename, ModeModify);
-	if IOResult(f) <> 0 then
-	begin
-		writeln('Error opening file: ', ErrorStr(IOResult(f)));
-		halt;
-	end
-	else
-	begin
-		write(f, h);
-		if IOResult(f) <> 0 then
-		begin
-			writeln('Error writing header: ', ErrorStr(IOResult(f)));
-			halt;
-		end;
-		close(f);	
-	end;
-end;
-
-procedure modifyHeader(var filename:string;var h:ProgramHeader);
-var done:boolean;
-    ch:char;
-    changed:boolean;
-
-	function getNewValue(descr:string):integer;
-	var buf:string;
-	    v,e:integer;
-	begin
-		getNewValue := 0;
-		write('New ',descr, ' size (decimal)> ');
-		readln(buf);
-		val(buf, v, e);
-		if(e > 0 ) or (v <= 0) then
-			writeln('invalid size')
-		else
-			getNewValue := v;
-	end;
-	
-	procedure changeStackSize;
-	var v:integer;
-	begin
-		v := getNewValue('stack');
-		if v > 0 then
-		begin
-			h.stackSize := v;
-			changed := true;
-		end;	
-	end;
-
-	procedure changeHeapSize;
-	var v:integer;
-	begin
-		v := getNewValue('heap');
-		if v > 0 then
-		begin
-			h.heapSize := v;
-			changed := true;
-		end;
-	end;
-
-begin
-	changed := false; done := false;
-
-	while not done do
-	begin
-		writeln(filename, ' header:');
-		showHeader(h);
-		writeln('Change H)eap size   Change S)tack size   eX)it');
-		write('> ');
-		read(ch);
-		writeln;
-		case upcase(ch) of
-		'S': changeStackSize;
-		'H': changeHeapSize;
-		'X': done := true;
-		else
-			writeln('invalid command');
-		end;
-	end;
-
-	if changed then
-		writeHeader(filename, h);
-end;
-
-begin
-	if ParamCount > 0 then
-		filename := ParamStr(1)
-	else
-	begin
-		write('File name> ');
-		readln(filename);
-	end;
-
-	readHeader(filename, h);
-
-	if h.magic <> ProgramMagic then
-		writeln('invalid magic value ', h.magic)
-	else
-		modifyHeader(filename, h);
-end.
--- a/progs/dumpdir.pas
+++ b/progs/dumpdir.pas
@ -14,8 +14,8 @@ var dirs:DirectorySlot;
    error:integer;
 begin
 	lastSlot := volumeTable[volid].part.dirSize - 1;
-	openvolumeid(volid, error); (* we just ignore error here because
-		we should always have enough heap space *)
+	openvolumeid(volid);
+
 	for i := 0 to lastSlot do
 	begin
 		getdirslot(volid, i, dirs, error);
--- a/progs/reclaim.pas
+++ b/progs/reclaim.pas
@ -123,8 +123,7 @@ begin
 		freeAreaCount := 0;
 		lastUsed := 0;

-		openvolumeid(volid, error);
-			(* ignoring theoretically possible out-of-heap-error *)
+		openvolumeid(volid);
 		i := 0;
 		endSlot := volumeTable[volid].part.dirSize - 1;

@ -309,7 +308,7 @@ begin
 		writeln('Volume ', volname, ' not found.')
 	else
 	begin
-		openvolumeid(volid, error);
+		openvolumeid(volid);

 		endSlot := volumeTable[volid].part.dirSize - 1;
 		extentSize := volumeTable[volid].part.extentSize;
--- a/progs/recover.pas
+++ b/progs/recover.pas
@ -1,167 +0,0 @@
-(* Copyright 2025 Sebastian Lederer. See the file LICENSE.md for details *)
-program recover;
-const PageMargin = 4;
-var filename:string;
-    volid:integer;
-
-(* we use some stuff internal to stdlib.pas *)
-procedure getdirslot(volumeid:integer;slotNo:integer;var result:DirectorySlot;var error:integer);
-	external;
-procedure openfile(volid:integer; slotno:integer; var dirslot:DirectorySlot; var aFile:File; mode:filemode);
-	external;
-
-function openvolume:integer;
-var volid:integer;
-begin
-	openvolume := -1;
-
-	volid := findvolume(DefaultVolume);
-	if volid < 1 then
-		writeln('Volume ', DefaultVolume, ' not found.')
-	else
-		openvolume := volid;
-end;
-
-procedure waitForKey;
-var c:char;
-begin
-	writeln;
-	writeln('-- press any key to continue --');
-	c := conin;
-end;
-
-procedure copyfile(volid:integer;slotno:integer;oldname,newname:string);
-var srcfile,destfile:file;
-    dirslot:DirectorySlot;
-    error:integer;
-    ch:char;
-    count:integer;
-begin
-	(* to open the deleted source file, we emulate parts
-		of the open procedure from stdlib *)
-	getdirslot(volid, slotno, dirslot, error);
-	if not (SlotDeleted in dirslot.flags)  or (dirslot.name <> oldname) then
-		writeln('Invalid slot ', slotno)
-	else
-	begin
-		openfile(volid, slotno, dirslot, srcfile, ModeReadOnly);
-		if error <> 0 then
-			writeln('Error opening file from slot ', slotno,
-				': ', ErrorStr(error))
-		else
-		begin
-			open(destfile, newname, ModeCreate);
-			if IOResult(destfile) = IOFileExists then
-			begin
-				write('File ', newname, ' already exists, overwrite? [y/n] ');
-				readln(ch);
-				if ch in ['Y', 'y'] then
-					open(destfile, newname, ModeOverwrite);
-			end;
-			if IOResult(destfile) <> 0 then
-				writeln('Error opening ', newname, ': ',
-					ErrorStr(IOResult(destfile)))
-			else
-			begin
-				(* taken from shell.pas copyFile *)
-				write('Recovering from slot ', slotno, ' to ', newname, '...');
-				count := 0;
-				while not eof(srcfile) do
-				begin
-					read(srcfile,ch);
-					write(destfile,ch);
-					count := count + 1;
-					if (count and 8191) = 0 then write('.');
-				end;
-				writeln;
-				close(destfile);
-			end;
-			close(srcfile);
-		end;
-	end;
-end;
-
-procedure recoverfile(volid:integer;wantedname:string);
-var dirs:DirectorySlot;
-    i:integer;
-    lastSlot:integer;
-    error:integer;
-    screenW,screenH:integer;
-    count:integer;
-    datestr:string;
-    ftime:DateTime;
-    wantedslot:integer;
-    newname:string;
-    foundsomething:boolean;
-begin
-	writeln('Files available for recovery:');
-	foundsomething := false;
-	newname := '';
-
-	GetTermSize(screenW, screenH);
-	count := PageMargin;
-
-	lastSlot := volumeTable[volid].part.dirSize - 1;
-	openvolumeid(volid, error);
-		(* ignoring theoretically possible out-of-heap-space error *)
-	for i := 0 to lastSlot do
-	begin
-		getdirslot(volid, i, dirs, error);
-		with dirs do
-		begin
-			if (SlotFirst in flags) or (SlotDeleted in flags) then
-				if name = wantedname then
-				begin
-					ftime := GetDateTime(dirs.modTime);
-					datestr := DateStr(ftime) + ' ' + TimeStr(ftime, true);
-					write('slot ', i:4, name:34, sizeBytes:8, datestr:21, '  ');
-					if SlotFirst in flags then write('Cur');
-					if SlotExtent in flags then write('Extent');
-					if SlotReserved in flags then write('Resvd');
-					if SlotDeleted in flags then write('Del');
-					if SlotFree in flags then write('Free');
-					if SlotEndScan in flags then write('End');
-					writeln;
-					foundsomething := true;
-					count := count + 1;
-					if count >= screenH then
-					begin
-						count := PageMargin;
-						waitForKey;
-					end;
-					if SlotEndScan in flags then break;
-				end;
-		end;
-	end;
-
-	if foundsomething  then
-	begin
-		write('Slot no to recover> ');
-		readln(wantedslot);
-		if (wantedslot < 1) or (wantedslot >= volumeTable[volid].part.dirSize) then
-			writeln('Invalid slot number.')
-		else
-		begin
-			write('New filename> ');
-			readln(newname);
-		end;
-
-		if length(newname) > 0 then
-			copyfile(volid, wantedslot, wantedname, newname);
-	end;
-
-	closevolumeid(volid);
-end;
-
-begin
-	if ParamCount > 0 then
-		filename := ParamStr(1)
-	else
-	begin
-		write('Filename to recover> ');
-		readln(filename);
-	end;
-	volid := openvolume;
-	if volid > 0 then
-		recoverfile(volid, filename);
-end.
--- a/progs/shell.pas
+++ b/progs/shell.pas
@ -149,7 +149,7 @@ begin
 		count := PageMargin;

 		writeln('reading directory of ', DefaultVolume);
-		openvolumeid(volid, error);
+		openvolumeid(volid);
 		readdirfirst(volid, index, dirs, error);
 		while index > 0 do
 		begin
--- a/progs/xfer.pas
+++ b/progs/xfer.pas
@ -226,7 +226,6 @@ begin
 	if not invalid then
 	begin
 		open(xferFile, filename, ModeOverwrite);
-		blockNo := 0;
 		done := false;
 		repeat
 			serReadBlock(ok);
@ -399,7 +398,7 @@ begin
 		writeln('Volume ', DefaultVolume, ' not found.')
 	else
 	begin
-		openvolumeid(volid, error);
+		openvolumeid(volid);
 		readdirfirst(volid, index, dirs, error);
 		while (index > 0) and (error = 0) do
 		begin
--- a/2
+++ b/2
@ -1 +1 @@
-Subproject commit 73936b4167bad01642675252e53a096d80fa6b35
+Subproject commit b0cfc8334349d51f2610b24c023b6498be3fb17b
--- a/tridoracpu/tridoracpu.srcs/Arty-A7-35-Master.xdc
+++ b/tridoracpu/tridoracpu.srcs/Arty-A7-35-Master.xdc
@ -8,8 +8,8 @@ set_property -dict {PACKAGE_PIN E3 IOSTANDARD LVCMOS33} [get_ports clk]
 create_clock -period 10.000 -name sys_clk_pin -waveform {0.000 5.000} -add [get_ports clk]

 ## Switches
-#set_property -dict {PACKAGE_PIN A8 IOSTANDARD LVCMOS33} [get_ports sw0]
-#set_property -dict {PACKAGE_PIN C11 IOSTANDARD LVCMOS33} [get_ports sw1]
+set_property -dict {PACKAGE_PIN A8 IOSTANDARD LVCMOS33} [get_ports sw0]
+set_property -dict {PACKAGE_PIN C11 IOSTANDARD LVCMOS33} [get_ports sw1]
 #set_property -dict { PACKAGE_PIN C10   IOSTANDARD LVCMOS33 } [get_ports { sw[2] }]; #IO_L13N_T2_MRCC_16 Sch=sw[2]
 #set_property -dict { PACKAGE_PIN A10   IOSTANDARD LVCMOS33 } [get_ports { sw[3] }]; #IO_L14P_T2_SRCC_16 Sch=sw[3]

@ -34,7 +34,7 @@ set_property -dict {PACKAGE_PIN T9 IOSTANDARD LVCMOS33} [get_ports led2]
 set_property -dict {PACKAGE_PIN T10 IOSTANDARD LVCMOS33} [get_ports led3]

 ## Buttons
-#set_property -dict {PACKAGE_PIN D9 IOSTANDARD LVCMOS33} [get_ports btn0]
+set_property -dict {PACKAGE_PIN D9 IOSTANDARD LVCMOS33} [get_ports btn0]
 #set_property -dict { PACKAGE_PIN C9    IOSTANDARD LVCMOS33 } [get_ports { btn1 }]; #IO_L11P_T1_SRCC_16 Sch=btn[1]
 #set_property -dict { PACKAGE_PIN B9    IOSTANDARD LVCMOS33 } [get_ports { btn[2] }]; #IO_L11N_T1_SRCC_16 Sch=btn[2]
 #set_property -dict { PACKAGE_PIN B8    IOSTANDARD LVCMOS33 } [get_ports { btn[3] }]; #IO_L12P_T1_MRCC_16 Sch=btn[3]
@ -70,10 +70,10 @@ set_property -dict {PACKAGE_PIN V14 IOSTANDARD LVCMOS33} [get_ports VGA_VS_O]
 #set_property -dict { PACKAGE_PIN U13   IOSTANDARD LVCMOS33 } [get_ports { jc[7] }]; #IO_L23N_T3_A02_D18_14 Sch=jc_n[4]

 ## Pmod Header JD
-set_property -dict { PACKAGE_PIN D4    IOSTANDARD LVCMOS33 } [get_ports { amp2_ain }]; #IO_L11N_T1_SRCC_35 Sch=jd[1]
-set_property -dict { PACKAGE_PIN D3    IOSTANDARD LVCMOS33 } [get_ports { amp2_gain }]; #IO_L12N_T1_MRCC_35 Sch=jd[2]
+#set_property -dict { PACKAGE_PIN D4    IOSTANDARD LVCMOS33 } [get_ports { jd[0] }]; #IO_L11N_T1_SRCC_35 Sch=jd[1]
+#set_property -dict { PACKAGE_PIN D3    IOSTANDARD LVCMOS33 } [get_ports { jd[1] }]; #IO_L12N_T1_MRCC_35 Sch=jd[2]
 #set_property -dict { PACKAGE_PIN F4    IOSTANDARD LVCMOS33 } [get_ports { jd[2] }]; #IO_L13P_T2_MRCC_35 Sch=jd[3]
-set_property -dict { PACKAGE_PIN F3    IOSTANDARD LVCMOS33 } [get_ports { amp2_shutdown_n }]; #IO_L13N_T2_MRCC_35 Sch=jd[4]
+#set_property -dict { PACKAGE_PIN F3    IOSTANDARD LVCMOS33 } [get_ports { jd[3] }]; #IO_L13N_T2_MRCC_35 Sch=jd[4]
 #set_property -dict { PACKAGE_PIN E2    IOSTANDARD LVCMOS33 } [get_ports { jd[4] }]; #IO_L14P_T2_SRCC_35 Sch=jd[7]
 #set_property -dict { PACKAGE_PIN D2    IOSTANDARD LVCMOS33 } [get_ports { jd[5] }]; #IO_L14N_T2_SRCC_35 Sch=jd[8]
 #set_property -dict { PACKAGE_PIN H2    IOSTANDARD LVCMOS33 } [get_ports { jd[6] }]; #IO_L15P_T2_DQS_35 Sch=jd[9]
--- a/tridoracpu/tridoracpu.srcs/dram_bridge.v
+++ b/tridoracpu/tridoracpu.srcs/dram_bridge.v
@ -107,14 +107,8 @@ module dram_bridge #(ADDR_WIDTH = 32, WIDTH = 32)
    );

    (*KEEP*) reg [DRAM_DATA_WIDTH-1:0] 	ins_cache;
-    (*KEEP*) reg [DRAM_ADDR_WIDTH-1:4]  icached_addr;
-    (*KEEP*) wire                       icache_hit = mem_read_enable && mem_read_ins && (icached_addr == mem_addr[DRAM_ADDR_WIDTH-1:4]);
-
-    (*KEEP*) reg [DRAM_DATA_WIDTH-1:0] 	d_cache;
-    (*KEEP*) reg [DRAM_ADDR_WIDTH-1:4]  dcached_addr;
-    (*KEEP*) wire                       dcache_hit = mem_read_enable && !mem_read_ins && (dcached_addr == mem_addr[DRAM_ADDR_WIDTH-1:4]);
-
-    wire cache_hit = icache_hit | dcache_hit;
+    (*KEEP*) reg [DRAM_ADDR_WIDTH-1:4]  cached_addr;
+    (*KEEP*) wire 		      	        cache_hit = mem_read_enable && mem_read_ins && (cached_addr == mem_addr[DRAM_ADDR_WIDTH-1:4]);

    reg [WIDTH-1:0] read_buf;
    reg read_inprogress = 0;
@ -131,32 +125,25 @@ module dram_bridge #(ADDR_WIDTH = 32, WIDTH = 32)
    wire [1:0] word_sel = mem_addr[3:2];

    wire [WIDTH-1:0] read_word =
-                        word_sel == 2'b11 ? app_rd_data[31:0]  :
-                        word_sel == 2'b10 ? app_rd_data[63:32] :
-                        word_sel == 2'b01 ? app_rd_data[95:64] :
+                        word_sel == 3'b11 ? app_rd_data[31:0]  :
+                        word_sel == 3'b10 ? app_rd_data[63:32] :
+                        word_sel == 3'b01 ? app_rd_data[95:64] :
                                            app_rd_data[127:96];

-    wire [WIDTH-1:0] read_icached_word =
-                        word_sel == 2'b11 ? ins_cache[31:0]  :
-                        word_sel == 2'b10 ? ins_cache[63:32] :
-                        word_sel == 2'b01 ? ins_cache[95:64] :
+    wire [WIDTH-1:0] read_cached_word =
+                        word_sel == 3'b11 ? ins_cache[31:0]  :
+                        word_sel == 3'b10 ? ins_cache[63:32] :
+                        word_sel == 3'b01 ? ins_cache[95:64] :
                                            ins_cache[127:96];

-    wire [WIDTH-1:0] read_dcached_word =
-                        word_sel == 2'b11 ? d_cache[31:0]  :
-                        word_sel == 2'b10 ? d_cache[63:32] :
-                        word_sel == 2'b01 ? d_cache[95:64] :
-                                            d_cache[127:96];
-
-    (*KEEP*) assign mem_read_data = icache_hit ? read_icached_word :
-                            dcache_hit ? read_dcached_word :
+    (*KEEP*) assign mem_read_data = cache_hit ? read_cached_word :
                            app_rd_data_valid ? read_word : read_buf;

    // set the write mask according to the lower bits of the address
    // (ignoring bit 0)
-    assign app_wdf_mask = word_sel == 2'b11 ? 16'b1111111111110000 :
-                          word_sel == 2'b10 ? 16'b1111111100001111 :
-                          word_sel == 2'b01 ? 16'b1111000011111111 :
+    assign app_wdf_mask = word_sel == 3'b11 ? 16'b1111111111110000 :
+                          word_sel == 3'b10 ? 16'b1111111100001111 :
+                          word_sel == 3'b01 ? 16'b1111000011111111 :
                                              16'b0000111111111111 ;

    wire write_ready = mem_write_enable & app_wdf_rdy & app_rdy;
@ -173,58 +160,25 @@ module dram_bridge #(ADDR_WIDTH = 32, WIDTH = 32)
    assign app_cmd = dram_read_enable ? CMD_READ : CMD_WRITE;


-    /* set instruction cache */
    always @(posedge dram_front_clk)
    begin
        if(dram_read_enable && mem_read_ins && app_rd_data_valid)
        begin
            ins_cache <= app_rd_data;
-            icached_addr <= mem_addr[DRAM_ADDR_WIDTH-1:4];
+            cached_addr <= mem_addr[DRAM_ADDR_WIDTH-1:4];
        end
    end

-    /* set data cache */
-    always @(posedge dram_front_clk)
-    begin
-        if(dram_read_enable && !mem_read_ins && app_rd_data_valid)
-        begin
-            d_cache <= app_rd_data;
-            dcached_addr <= mem_addr[DRAM_ADDR_WIDTH-1:4];
-        end
-        
-        /* write-through cache - invalidate on write */
-        /* invalidate data cache on write */
-//         if(mem_write_enable && dcached_addr == mem_addr[DRAM_ADDR_WIDTH-1:4])
-//            dcached_addr <= {DRAM_ADDR_WIDTH-4{1'b1}};
-
-        /* write-back cache - update cache on write */
-        // write back to data cache on mem_write
-        if(mem_write_enable && dcached_addr == mem_addr[DRAM_ADDR_WIDTH-1:4])
-        begin
-            case(word_sel)
-                2'b11: d_cache[31:0] <= mem_write_data;
-                2'b10: d_cache[63:32] <= mem_write_data;
-                2'b01: d_cache[95:64] <= mem_write_data;
-                2'b00: d_cache[127:96] <= mem_write_data;
-            endcase            
-        end
-    end
-
-    /* transfer read data, either from cache or from DRAM */
    always @(posedge dram_front_clk)
    begin
        if(dram_read_enable & ~read_inprogress & app_rdy)
            read_inprogress <= 1;
        if(read_inprogress & app_rd_data_valid)
            read_inprogress <= 0;
-
        if(dram_read_enable & app_rd_data_valid)
            read_buf <= mem_read_data;
        else
-        if (mem_read_enable & icache_hit)
-            read_buf <= read_icached_word;
-        else
-        if (mem_read_enable & dcache_hit)
-            read_buf <= read_dcached_word;
+        if (mem_read_enable & cache_hit)
+            read_buf <= read_cached_word;
    end
 endmodule
--- a/tridoracpu/tridoracpu.srcs/irqctrl.v
+++ b/tridoracpu/tridoracpu.srcs/irqctrl.v
@ -1,6 +1,6 @@
 `timescale 1ns / 1ps

-module irqctrl #(IRQ_LINES = 3, IRQ_DELAY_WIDTH = 4) (
+module irqctrl #(IRQ_LINES = 2, IRQ_DELAY_WIDTH = 4) (
        input wire clk,
        input wire [IRQ_LINES-1:0] irq_in,
        input wire cs,
--- a/tridoracpu/tridoracpu.srcs/mem.v
+++ b/tridoracpu/tridoracpu.srcs/mem.v
@ -91,10 +91,8 @@ module mem #(parameter ADDR_WIDTH = 32,
  // RAM1 $1000 - $FFFF 60K
  // RAM2 $10000 - $FFFFFFFF ~4GB

-  localparam RAM1_ADDR_WIDTH = 16;
-
  wire ram_cs = addr[ADDR_WIDTH-1:12] != { {(ADDR_WIDTH-12){1'b0}}};
-  wire ram1_cs = ram_cs && (addr[ADDR_WIDTH-1:RAM1_ADDR_WIDTH] == { {(ADDR_WIDTH-RAM1_ADDR_WIDTH){1'b0}}});
+  wire ram1_cs = ram_cs && (addr[ADDR_WIDTH-1:16] == { {(ADDR_WIDTH-16){1'b0}}});
  wire ram2_cs = ram_cs && !ram1_cs;
  wire rom_cs = !ram_cs && addr[11] == 1'b0;
  wire io_cs = !ram_cs && addr[11]  == 1'b1;
@ -118,10 +116,10 @@ module mem #(parameter ADDR_WIDTH = 32,
  // test
  reg [1:0] wait_state;

-  ram32 #(.ADDR_WIDTH(RAM1_ADDR_WIDTH)) ram0  // 64KB RAM
+  ram32 #(.ADDR_WIDTH(16)) ram0  // 64KB RAM
  (
    .clk(clk),
-    .addr(addr[RAM1_ADDR_WIDTH-1:0]),
+    .addr(addr[15:0]),
    .data_out(ram_out),
    .read_enable(ram_read),
    .data_in(data_in),
--- a/tridoracpu/tridoracpu.srcs/stackcpu.v
+++ b/tridoracpu/tridoracpu.srcs/stackcpu.v
@ -16,11 +16,11 @@ module stackcpu #(parameter ADDR_WIDTH = 32, WIDTH = 32,
    output wire write_enable,
    input wire mem_wait,
    
-    output wire debug1,
-    output wire debug2,
-    output wire debug3
+    output wire led1,
+    output wire led2,
+    output wire led3
    );
-
+    
    localparam EVAL_STACK_INDEX_WIDTH = 6;

    wire reset = !rst;
@ -90,6 +90,7 @@ module stackcpu #(parameter ADDR_WIDTH = 32, WIDTH = 32,
    wire mem_write;
    
    wire x_is_zero;
+    // wire [WIDTH-1:0] y_plus_operand = Y + operand;

    wire x_equals_y = X == Y;
    wire y_lessthan_x  = $signed(Y) < $signed(X);
@ -104,10 +105,16 @@ module stackcpu #(parameter ADDR_WIDTH = 32, WIDTH = 32,
    assign write_enable = mem_write_enable;

    // debug output ------------------------------------------------------------------------------------
-    assign debug1 = reset;
-    assign debug2 = ins_loadc;
-    assign debug3 = ins_branch;
-
+    assign led1 = reset;
+    assign led2 = ins_loadc;
+    assign led3 = ins_branch;
+//    assign debug_out1 = { mem_read_enable, mem_write_enable, x_is_zero,
+//                    ins_branch, ins_aluop, y_lessthan_x, x_equals_y, {7{1'b0}}, seq_state};
+//    assign debug_out2 = data_in;
+//    assign debug_out3 = nX;
+//    assign debug_out4 = nPC;
+//    assign debug_out5 = ins;
+//    assign debug_out6 = IV;
    //--------------------------------------------------------------------------------------------------

    // instruction decoding
--- a/tridoracpu/tridoracpu.srcs/tdraudio.v
+++ b/tridoracpu/tridoracpu.srcs/tdraudio.v
@ -1,270 +0,0 @@
-`timescale 1ns / 1ps
-
-// waveform generator module (PCM)
-module wavegen #(DATA_WIDTH=32, CLOCK_DIV_WIDTH=22,
-    AMP_WIDTH=16, AMP_BIAS=32768) (
-        input wire clk,
-        input wire reset,
-        input wire [1:0] reg_sel,
-        output wire [DATA_WIDTH-1:0] rd_data,
-        input wire [AMP_WIDTH-1:0] wr_data,
-        input wire rd_en,
-        input wire wr_en,
-
-        output wire [AMP_WIDTH-1:0] amp_val,
-        output wire running,
-        output wire irq
-    );
-
-    localparam TDRAU_REG_CTL = 0;  /* control register */
-    localparam TDRAU_REG_CLK = 1;  /* clock divider register */
-    localparam TDRAU_REG_AMP = 2;  /* amplitude (volume) register */
-
-     /* avoid warning about unconnected port */
-    (* keep="soft" *) wire _unused = rd_en;
-
-    reg channel_enable;
-    reg [CLOCK_DIV_WIDTH-1:0] clock_div;
-    reg [CLOCK_DIV_WIDTH-1:0] div_count;
-    reg amp_phase;
-    reg [AMP_WIDTH-1:0] amp_out;
-
-
-    wire fifo_wr_en;
-    wire fifo_rd_en, fifo_full, fifo_empty;
-    wire [AMP_WIDTH-1:0] fifo_rd_data;
-
-    fifo #(.ADDR_WIDTH(4), .DATA_WIDTH(16)) sample_buf(
-        clk, reset,
-        fifo_wr_en, fifo_rd_en,
-        wr_data[AMP_WIDTH-1:0], fifo_rd_data,
-        fifo_full,
-        fifo_empty
-    );
-
-    assign fifo_rd_en = (div_count == 0) && channel_enable && ~fifo_empty;
-    assign fifo_wr_en = wr_en && (reg_sel == TDRAU_REG_AMP);
-
-    reg irq_buf, irq_enable;
-    assign irq = channel_enable && irq_buf;
-
-    reg [DATA_WIDTH-1:0] rd_data_buf;
-    assign rd_data = rd_data_buf;
-
-    assign amp_val = amp_out;
-    assign running = channel_enable;
-
-    wire ctl_reg_write = wr_en && (reg_sel == TDRAU_REG_CTL);
-
-    /* update read data buffer */
-    always @(posedge clk)
-    begin
-        rd_data_buf <= {{DATA_WIDTH-8{1'b0}},
-            {3{1'b0}}, irq_enable, fifo_full, fifo_empty, amp_phase, channel_enable};
-    end
-
-    /* irq signal to interrupt controller */
-    always @(posedge clk)
-    begin
-        if(reset)
-            irq_buf <= 0;
-        else
-        if(fifo_empty && irq_enable)
-            irq_buf <= 1;
-        else
-            irq_buf <= 0;
-    end
-
-    /* interrupt enable flag  */
-    always @(posedge clk)
-    begin
-        if(reset)
-            irq_enable <= 0;
-        else
-        if(ctl_reg_write)
-            irq_enable <= wr_data[4];
-        else
-        if(irq_buf)
-            irq_enable <= 0;  // disable interrupts after an interrupt
-    end
-
-    /* channel enable flag */
-    always @(posedge clk)
-    begin
-        if(reset)
-            channel_enable <= 0;
-        else if (ctl_reg_write)
-            channel_enable <= wr_data[0];
-    end
-
-    /* clock divider register */
-    always @(posedge clk)
-    begin
-        if(reset)
-            clock_div <= 0;
-        else
-        if (wr_en && (reg_sel == TDRAU_REG_CLK))
-             clock_div <= wr_data;
-    end
-
-    /* divider counter */
-    always @(posedge clk)
-    begin
-        if(channel_enable)
-        begin
-            if(div_count == 0)      // reset counter if it reaches zero
-                div_count <= clock_div;
-            else
-                div_count <= div_count - 1;  // else just decrement it
-        end
-        else
-        if (wr_en && (reg_sel == TDRAU_REG_CLK)) // when setting divider,
-                div_count <= 1; // start cycle on next clock tick
-    end
-
-    /* amplitude out */
-    always @(posedge clk)
-    begin
-        if (reset)
-        begin
-            amp_out <= AMP_BIAS;
-            amp_phase <= 1;
-        end
-        else
-        if (channel_enable)
-        begin
-            if (div_count == 0) // invert amplitude on clock tick
-            begin
-                amp_out <=  fifo_rd_data;
-                amp_phase <= ~amp_phase;
-            end
-        end
-        else
-            amp_out <= AMP_BIAS;
-
-        // reset phase bit when enabling the channel
-        if (ctl_reg_write && wr_data[0] && ~channel_enable)
-            // when channel is being enabled, phase will be flipped on next tick
-            // because div_count will become zero
-            amp_phase <= 1;
-    end
-endmodule
-
-module tdraudio #(DATA_WIDTH=32) (
-        input wire clk,
-        input wire reset,
-        input wire [6:0] io_addr,
-        output wire [DATA_WIDTH-1:0] rd_data,
-        input wire [DATA_WIDTH-1:0] wr_data,
-        input wire rd_en,
-        input wire wr_en,
-        output wire irq_out,
-        output wire pdm_out,
-        output wire gain_sel,
-        output wire shutdown_n
-    );
-
-    localparam CLOCK_DIV_WIDTH = 22;
-    localparam AMP_WIDTH = 16;
-    localparam AMP_BIAS = 32768;
-    localparam DAC_WIDTH = 18;
-
-     /* avoid warning about unconnected port */
-    (* keep="soft" *) wire [DATA_WIDTH-1:AMP_WIDTH] _unused = wr_data[DATA_WIDTH-1:AMP_WIDTH];
-
-    wire [4:0] chan_sel = io_addr[6:2];
-    wire [1:0] reg_sel = io_addr[1:0];
-
-    wire [AMP_WIDTH-1:0] amp_wr_data = wr_data[AMP_WIDTH-1:0];
-
-    wire [AMP_WIDTH-1:0] chan0_amp;
-    wire [DATA_WIDTH-1:0] chan0_rd_data;
-    wire chan0_running;
-    wire chan0_irq;
-    wire chan0_sel = chan_sel == 5'd0;
-    wire chan0_rd_en = chan0_sel && rd_en;
-    wire chan0_wr_en = chan0_sel && wr_en;
-
-    wire [AMP_WIDTH-1:0] chan1_amp;
-    wire [DATA_WIDTH-1:0] chan1_rd_data;
-    wire chan1_running;
-    wire chan1_irq;
-    wire chan1_sel = chan_sel == 5'd1;
-    wire chan1_rd_en = chan1_sel && rd_en;
-    wire chan1_wr_en = chan1_sel && wr_en;
-
-    wire [AMP_WIDTH-1:0] chan2_amp;
-    wire [DATA_WIDTH-1:0] chan2_rd_data;
-    wire chan2_running;
-    wire chan2_irq;
-    wire chan2_sel = chan_sel == 5'd2;
-    wire chan2_rd_en = chan2_sel && rd_en;
-    wire chan2_wr_en = chan2_sel && wr_en;
-
-    wire [AMP_WIDTH-1:0] chan3_amp;
-    wire [DATA_WIDTH-1:0] chan3_rd_data;
-    wire chan3_running;
-    wire chan3_irq;
-    wire chan3_sel = chan_sel == 5'd3;
-    wire chan3_rd_en = chan3_sel && rd_en;
-    wire chan3_wr_en = chan3_sel && wr_en;
-
-    wire running = chan0_running || chan1_running || chan2_running || chan3_running;
-
-    assign rd_data = chan0_sel ? chan0_rd_data :
-                        chan1_sel ? chan1_rd_data :
-                        chan2_sel ? chan2_rd_data :
-                        chan3_sel ? chan3_rd_data :
-                        {DATA_WIDTH{1'b1}};
-
-    wavegen chan0(clk, reset, reg_sel,
-        chan0_rd_data, amp_wr_data,
-        chan0_rd_en, chan0_wr_en,
-        chan0_amp,
-        chan0_running, chan0_irq);
-
-    wavegen chan1(clk, reset, reg_sel,
-        chan1_rd_data, amp_wr_data,
-        chan1_rd_en, chan1_wr_en,
-        chan1_amp,
-        chan1_running, chan1_irq);
-
-    wavegen chan2(clk, reset, reg_sel,
-        chan2_rd_data, amp_wr_data,
-        chan2_rd_en, chan2_wr_en,
-        chan2_amp,
-        chan2_irq, chan2_running);
-
-    wavegen chan3(clk, reset, reg_sel,
-        chan3_rd_data, amp_wr_data,
-        chan3_rd_en, chan3_wr_en,
-        chan3_amp,
-        chan3_running, chan3_irq);
-
-    reg [DAC_WIDTH:0] deltasigma_acc; // one extra bit
-    wire [DAC_WIDTH:0] amp_sum = chan0_amp + chan1_amp + chan2_amp + chan3_amp; // also one overflow bit here
-    assign gain_sel = 1;  // gain select: 0 -> 12dB, 1 -> 6dB
-
-    // assign shutdown_n = running;
-    assign shutdown_n = 1;  /* don't enable shutdown mode, it creates a mains hum */
-
-    reg irq_out_buf;
-    assign irq_out = irq_out_buf;
-
-    always @(posedge clk) irq_out_buf <= chan0_irq || chan1_irq || chan2_irq || chan3_irq;
-
-    /* delta-sigma DAC */
-    always @(posedge clk)
-    begin
-        if(reset)
-            deltasigma_acc <= 0;
-        else
-//        if (running)
-            deltasigma_acc <= deltasigma_acc[DAC_WIDTH-1:0] + amp_sum;
-//        else
-//            deltasigma_acc <= deltasigma_acc[DAC_WIDTH-1:0] + (4*AMP_BIAS);
-    end
-
-    /* 1-bit audio output */
-    assign pdm_out = deltasigma_acc[DAC_WIDTH];
-endmodule
--- a/tridoracpu/tridoracpu.srcs/top.v
+++ b/tridoracpu/tridoracpu.srcs/top.v
@ -10,11 +10,13 @@
 //`define clock clk_1hz
 `define ENABLE_VGAFB
 `define ENABLE_MICROSD
-`define ENABLE_TDRAUDIO

 module top(
    input wire clk,
    input wire rst,
+    input wire btn0,
+    input wire sw0,
+    input wire sw1,
    output wire led0,
    output wire led1,
    output wire led2,
@ -58,13 +60,6 @@ module top(
    output wire sd_sck,
    input wire  sd_cd
 `endif
-
-`ifdef ENABLE_TDRAUDIO
-    ,
-    output wire amp2_ain,
-    output wire amp2_gain,
-    output wire amp2_shutdown_n
-`endif
 );

    reg clk_1hz;
@ -225,44 +220,11 @@ module top(
    assign uart_tx_data = mem_write_data[7:0];
    assign uart_rd_data = { {WIDTH-10{1'b1}}, uart_rx_avail, uart_tx_busy, uart_rx_data };

-    wire audio_irq;
-
-    buart #(.CLKFREQ(`clkfreq)) uart0(`clock, rst,
-        uart_baud,
-        uart_txd_in, uart_rxd_out,
-        uart_rx_clear, uart_tx_en,
-        uart_rx_avail, uart_tx_busy,
-        uart_tx_data, uart_rx_data);
-
-    // audio controller
-`ifdef ENABLE_TDRAUDIO
-    wire [WIDTH-1:0] tdraudio_wr_data;
-    wire [WIDTH-1:0] tdraudio_rd_data;
-    wire tdraudio_rd_en, tdraudio_wr_en;
-    wire tdraudio_irq;
-
-    wire tdraudio_cs_en = io_enable && (io_slot == 4);
-    assign tdraudio_rd_en = tdraudio_cs_en && mem_read_enable;
-    assign tdraudio_wr_en = tdraudio_cs_en && mem_write_enable;
-    assign tdraudio_wr_data = mem_write_data;
-
-    tdraudio tdraudio0(`clock, ~rst,
-        mem_addr[6:0],
-        tdraudio_rd_data,
-        tdraudio_wr_data,
-        tdraudio_rd_en,
-        tdraudio_wr_en,
-        tdraudio_irq,
-        amp2_ain, amp2_gain, amp2_shutdown_n);
-    assign audio_irq = tdraudio_irq;
-`endif
-
-    // interrupt controller
    reg timer_tick;
    reg[23:0] tick_count;
-    wire [2:0] irq_in = { audio_irq, timer_tick, uart_rx_avail };
-    wire [2:0] irqc_rd_data0;
-    wire [WIDTH-1:0] irqc_rd_data = { tick_count, 5'b0, irqc_rd_data0 };
+    wire [1:0] irq_in = { timer_tick, uart_rx_avail };
+    wire [1:0] irqc_rd_data0;
+    wire [WIDTH-1:0] irqc_rd_data = { tick_count, 6'b0, irqc_rd_data0 };
    wire irqc_seten = mem_write_data[7];
    wire irqc_cs = io_enable && (io_slot == 3);

@ -274,11 +236,16 @@ module top(
                        (io_slot == 2) ? fb_rd_data :
    `endif
                        (io_slot == 3) ? irqc_rd_data:
-    `ifdef ENABLE_TDRAUDIO
-                        (io_slot == 4) ? tdraudio_rd_data:
-    `endif
+
                        -1;

+    buart #(.CLKFREQ(`clkfreq)) uart0(`clock, rst,
+        uart_baud,
+        uart_txd_in, uart_rxd_out,
+        uart_rx_clear, uart_tx_en,
+        uart_rx_avail, uart_tx_busy,
+        uart_tx_data, uart_rx_data);
+
     // CPU -----------------------------------------------------------------
    stackcpu cpu0(.clk(`clock), .rst(rst), .irq(irq),
        .addr(mem_addr),
@ -286,7 +253,7 @@ module top(
        .read_ins(dram_read_ins),
        .data_out(mem_write_data), .write_enable(mem_write_enable),
        .mem_wait(mem_wait),
-        .debug1(led1), .debug2(led2), .debug3(led3));
+        .led1(led1), .led2(led2), .led3(led3));

    // Interrupt Controller
    irqctrl irqctrl0(`clock, irq_in, irqc_cs, mem_write_enable,
--- a/tridoracpu/tridoracpu.srcs/vgafb.v
+++ b/tridoracpu/tridoracpu.srcs/vgafb.v
@ -6,11 +6,8 @@
 // Learn more at https://projectf.io

 //128K video memory is not enough for 640x480x4
-//`define RES_640_400
+`define RES_640_400
 //`define RES_1024_768
-// RES_640_480 mode displays 400 lines with 640x480/60 video timings,
-// adding blank lines at the bottom
-`define RES_640_480

 module display_timings #(
    H_RES=640,                      // horizontal resolution (pixels)
@ -129,8 +126,6 @@ module vgafb #(VMEM_ADDR_WIDTH = 15, VMEM_DATA_WIDTH = 32) (
    localparam COLOR_WIDTH = 12;
    localparam PALETTE_WIDTH = 4;

-    localparam signed PIC_LINES = 400; // visible picture lines
-
    // Display Clocks
    wire pix_clk = CLK;                   // pixel clock
    wire clk_lock = 1;                  // clock locked?
@ -207,18 +202,6 @@ module vgafb #(VMEM_ADDR_WIDTH = 15, VMEM_DATA_WIDTH = 32) (
        .V_BP(35),
        .H_POL(0),
        .V_POL(1)
- `endif
- `ifdef RES_640_480
-        .H_RES(640),               //     640      800     1280      1920
-        .V_RES(480),                //     480      600      720      1080
-        .H_FP(16),                 //      16       40      110        88
-        .H_SYNC(96),                //      96      128       40        44
-        .H_BP(48),                 //      48       88      220       148
-        .V_FP(10),                   //      10        1        5         4
-        .V_SYNC(2),                 //       2        4        5         5
-        .V_BP(33),                  //      33       23       20        36
-        .H_POL(0),                  //       0        1        1         1
-        .V_POL(0)                   //       0        1        1         1
 `endif
    )
    display_timings_inst (
@ -234,8 +217,6 @@ module vgafb #(VMEM_ADDR_WIDTH = 15, VMEM_DATA_WIDTH = 32) (
        .o_sy(sy)
    );

-    wire pic_enable = (sy >= 0) && (sy < PIC_LINES);  // when to display pixels from VRAM
-
    wire [7:0] red;
    wire [7:0] green;
    wire [7:0] blue;
@ -307,7 +288,7 @@ module vgafb #(VMEM_ADDR_WIDTH = 15, VMEM_DATA_WIDTH = 32) (
    // 12 bit RGB palette
    assign VGA_HS   = h_sync;
    assign VGA_VS   = v_sync;
-    assign VGA_R    = (pic_enable && de) ? color_data[11:8] : 4'b0;
-    assign VGA_G    = (pic_enable && de) ? color_data[7:4]  : 4'b0;
-    assign VGA_B    = (pic_enable && de) ? color_data[3:0]  : 4'b0;
+    assign VGA_R    = de ? color_data[11:8] : 4'b0;
+    assign VGA_G    = de ? color_data[7:4]  : 4'b0;
+    assign VGA_B    = de ? color_data[3:0]  : 4'b0;
 endmodule
--- a/tridoracpu/tridoracpu.xpr
+++ b/tridoracpu/tridoracpu.xpr
@ -111,7 +111,7 @@
          <Attr Name="UsedIn" Val="implementation"/>
        </FileInfo>
      </File>
-      <File Path="$PSRCDIR/stack.v" Mode="RelativeOnly">
+      <File Path="$PSRCDIR/stack.v">
        <FileInfo>
          <Attr Name="UsedIn" Val="synthesis"/>
          <Attr Name="UsedIn" Val="implementation"/>
@ -142,7 +142,7 @@
        </FileInfo>
      </File>
      <File Path="$PSRCDIR/testbench.v"/>
-      <File Path="$PPRDIR/rom.mem" Mode="RelativeOnly">
+      <File Path="$PPRDIR/rom.mem">
        <FileInfo>
          <Attr Name="UsedIn" Val="synthesis"/>
          <Attr Name="UsedIn" Val="simulation"/>
@ -173,14 +173,14 @@
          <Attr Name="UsedIn" Val="simulation"/>
        </FileInfo>
      </File>
-      <File Path="$PSRCDIR/bram_tdp.v" Mode="RelativeOnly">
+      <File Path="$PSRCDIR/bram_tdp.v">
        <FileInfo>
          <Attr Name="UsedIn" Val="synthesis"/>
          <Attr Name="UsedIn" Val="implementation"/>
          <Attr Name="UsedIn" Val="simulation"/>
        </FileInfo>
      </File>
-      <File Path="$PSRCDIR/palette.v" Mode="RelativeOnly">
+      <File Path="$PSRCDIR/palette.v">
        <FileInfo>
          <Attr Name="UsedIn" Val="synthesis"/>
          <Attr Name="UsedIn" Val="implementation"/>
@ -205,13 +205,6 @@
          <Attr Name="UsedIn" Val="simulation"/>
        </FileInfo>
      </File>
-      <File Path="$PSRCDIR/tdraudio.v">
-        <FileInfo>
-          <Attr Name="UsedIn" Val="synthesis"/>
-          <Attr Name="UsedIn" Val="implementation"/>
-          <Attr Name="UsedIn" Val="simulation"/>
-        </FileInfo>
-      </File>
      <Config>
        <Option Name="DesignMode" Val="RTL"/>
        <Option Name="TopModule" Val="top"/>
@ -357,6 +350,16 @@
  </Simulators>
  <Runs Version="1" Minor="22">
    <Run Id="synth_1" Type="Ft3:Synth" SrcSet="sources_1" Part="xc7a35ticsg324-1L" ConstrsSet="constrs_1" Description="Vivado Synthesis Defaults" AutoIncrementalCheckpoint="false" WriteIncrSynthDcp="false" State="current" Dir="$PRUNDIR/synth_1" IncludeInArchive="true" IsChild="false" AutoIncrementalDir="$PSRCDIR/utils_1/imports/synth_1" AutoRQSDir="$PSRCDIR/utils_1/imports/synth_1" ParallelReportGen="true">
+      <Strategy Version="1" Minor="2">
+        <StratHandle Name="Vivado Synthesis Defaults" Flow="Vivado Synthesis 2020"/>
+        <Step Id="synth_design"/>
+      </Strategy>
+      <GeneratedRun Dir="$PRUNDIR" File="gen_run.xml"/>
+      <ReportStrategy Name="Vivado Synthesis Default Reports" Flow="Vivado Synthesis 2020"/>
+      <Report Name="ROUTE_DESIGN.REPORT_METHODOLOGY" Enabled="1"/>
+      <RQSFiles/>
+    </Run>
+    <Run Id="mig_dram_0_synth_1" Type="Ft3:Synth" SrcSet="mig_dram_0" Part="xc7a35ticsg324-1L" ConstrsSet="mig_dram_0" Description="Vivado Synthesis Defaults" AutoIncrementalCheckpoint="false" WriteIncrSynthDcp="false" Dir="$PRUNDIR/mig_dram_0_synth_1" IncludeInArchive="true" IsChild="false" AutoIncrementalDir="$PSRCDIR/utils_1/imports/mig_dram_0_synth_1" AutoRQSDir="$PSRCDIR/utils_1/imports/mig_dram_0_synth_1" ParallelReportGen="true">
      <Strategy Version="1" Minor="2">
        <StratHandle Name="Vivado Synthesis Defaults" Flow="Vivado Synthesis 2024">
          <Desc>Vivado Synthesis Defaults</Desc>
@ -368,41 +371,37 @@
      <Report Name="ROUTE_DESIGN.REPORT_METHODOLOGY" Enabled="1"/>
      <RQSFiles/>
    </Run>
-    <Run Id="mig_dram_0_synth_1" Type="Ft3:Synth" SrcSet="mig_dram_0" Part="xc7a35ticsg324-1L" ConstrsSet="mig_dram_0" Description="Vivado Synthesis Defaults" AutoIncrementalCheckpoint="false" WriteIncrSynthDcp="false" Dir="$PRUNDIR/mig_dram_0_synth_1" IncludeInArchive="true" IsChild="false" AutoIncrementalDir="$PSRCDIR/utils_1/imports/mig_dram_0_synth_1" AutoRQSDir="$PSRCDIR/utils_1/imports/mig_dram_0_synth_1" ParallelReportGen="true">
+    <Run Id="impl_1" Type="Ft2:EntireDesign" Part="xc7a35ticsg324-1L" ConstrsSet="constrs_1" Description="Increase placer effort in the post-placement optimization phase, and disable timing relaxation in the router." AutoIncrementalCheckpoint="false" WriteIncrSynthDcp="false" State="current" Dir="$PRUNDIR/impl_1" SynthRun="synth_1" IncludeInArchive="true" IsChild="false" GenFullBitstream="true" AutoIncrementalDir="$PSRCDIR/utils_1/imports/impl_1" LaunchOptions="-jobs 6 " AutoRQSDir="$PSRCDIR/utils_1/imports/impl_1" ParallelReportGen="true">
      <Strategy Version="1" Minor="2">
-        <StratHandle Name="Vivado Synthesis Defaults" Flow="Vivado Synthesis 2024"/>
-        <Step Id="synth_design"/>
-      </Strategy>
-      <GeneratedRun Dir="$PRUNDIR" File="gen_run.xml"/>
-      <ReportStrategy Name="Vivado Synthesis Default Reports" Flow="Vivado Synthesis 2024"/>
-      <Report Name="ROUTE_DESIGN.REPORT_METHODOLOGY" Enabled="1"/>
-      <RQSFiles/>
-    </Run>
-    <Run Id="impl_1" Type="Ft2:EntireDesign" Part="xc7a35ticsg324-1L" ConstrsSet="constrs_1" Description="Default settings for Implementation." AutoIncrementalCheckpoint="false" WriteIncrSynthDcp="false" State="current" Dir="$PRUNDIR/impl_1" SynthRun="synth_1" IncludeInArchive="true" IsChild="false" GenFullBitstream="true" AutoIncrementalDir="$PSRCDIR/utils_1/imports/impl_1" LaunchOptions="-jobs 6 " AutoRQSDir="$PSRCDIR/utils_1/imports/impl_1" ParallelReportGen="true">
-      <Strategy Version="1" Minor="2">
-        <StratHandle Name="Vivado Implementation Defaults" Flow="Vivado Implementation 2024">
-          <Desc>Default settings for Implementation.</Desc>
-        </StratHandle>
+        <StratHandle Name="Performance_RefinePlacement" Flow="Vivado Implementation 2020"/>
        <Step Id="init_design"/>
        <Step Id="opt_design"/>
        <Step Id="power_opt_design"/>
-        <Step Id="place_design"/>
+        <Step Id="place_design">
+          <Option Id="Directive">7</Option>
+        </Step>
        <Step Id="post_place_power_opt_design"/>
-        <Step Id="phys_opt_design"/>
-        <Step Id="route_design"/>
+        <Step Id="phys_opt_design">
+          <Option Id="Directive">0</Option>
+        </Step>
+        <Step Id="route_design">
+          <Option Id="Directive">0</Option>
+        </Step>
        <Step Id="post_route_phys_opt_design"/>
        <Step Id="write_bitstream">
          <Option Id="BinFile">1</Option>
        </Step>
      </Strategy>
      <GeneratedRun Dir="$PRUNDIR" File="gen_run.xml"/>
-      <ReportStrategy Name="Vivado Implementation Default Reports" Flow="Vivado Implementation 2024"/>
+      <ReportStrategy Name="Vivado Implementation Default Reports" Flow="Vivado Implementation 2020"/>
      <Report Name="ROUTE_DESIGN.REPORT_METHODOLOGY" Enabled="1"/>
      <RQSFiles/>
    </Run>
    <Run Id="mig_dram_0_impl_1" Type="Ft2:EntireDesign" Part="xc7a35ticsg324-1L" ConstrsSet="mig_dram_0" Description="Default settings for Implementation." AutoIncrementalCheckpoint="false" WriteIncrSynthDcp="false" SynthRun="mig_dram_0_synth_1" IncludeInArchive="false" IsChild="false" GenFullBitstream="true" AutoIncrementalDir="$PSRCDIR/utils_1/imports/mig_dram_0_impl_1" AutoRQSDir="$PSRCDIR/utils_1/imports/mig_dram_0_impl_1" ParallelReportGen="true">
      <Strategy Version="1" Minor="2">
-        <StratHandle Name="Vivado Implementation Defaults" Flow="Vivado Implementation 2024"/>
+        <StratHandle Name="Vivado Implementation Defaults" Flow="Vivado Implementation 2024">
+          <Desc>Default settings for Implementation.</Desc>
+        </StratHandle>
        <Step Id="init_design"/>
        <Step Id="opt_design"/>
        <Step Id="power_opt_design"/>
--- a/tridoraemu/ADDS-Envoy-620.pict
+++ b/tridoraemu/ADDS-Envoy-620.pict
--- a/tridoraemu/cpu.go
+++ b/tridoraemu/cpu.go
@ -125,7 +125,7 @@ func (c *CPU) step() error {
 	
 	Y := c.estack[c.ESP]

-	insWord, err := c.mem.readIns(c.PC)
+	insWord, err := c.mem.read(c.PC)
 	if err != nil { return err }
 	if c.PC % 4 == 0 {
 		insWord = insWord >> 16
--- a/tridoraemu/mem.go
+++ b/tridoraemu/mem.go
@ -17,12 +17,6 @@ const IOSlotSize = 128

 const IOSlotCount = 16

-const DRAMStart = 65536
-
-const CacheAddrShift = 8
-
-const CacheWriteThrough = true
-
 type Mem struct {
 	ram [] word
 	iohandler [IOSlotCount] IOHandler
@ -85,7 +79,7 @@ func (m *Mem) attachIO(h IOHandler, slot int) {
 	m.iohandler[slot] = h
 }

-func (m *Mem) readRaw(byteaddr word) (word, error) {
+func (m *Mem) read(byteaddr word) (word, error) {
 	if byteaddr >= IOStartAddr && byteaddr < RAMStartAddr {
 		ioslot := (byteaddr - IOStartAddr) / IOSlotSize
 		if m.iohandler[ioslot] != nil {
@ -102,14 +96,6 @@ func (m *Mem) readRaw(byteaddr word) (word, error) {
 	}
 }

-func (m *Mem) read(byteaddr word) (word, error) {
-	return m.readRaw(byteaddr);
-}
-
-func (m *Mem) readIns(byteaddr word) (word, error) {
-	return m.readRaw(byteaddr);
-}
-
 func (m *Mem) write(value word, byteaddr word) error {
 	if byteaddr < IOStartAddr {
 		return fmt.Errorf("Write to ROM area at %08X value %08X", byteaddr, value)
--- a/tridoraemu/tridoraemu.go
+++ b/tridoraemu/tridoraemu.go
@ -8,8 +8,7 @@ import (
 	"flag"
 	"time"
 	"github.com/hajimehoshi/ebiten/v2"
-	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
-	"github.com/hajimehoshi/ebiten/v2/inpututil"
+	// "github.com/hajimehoshi/ebiten/v2/ebitenutil"
 	// "image/color"
 )

@ -36,7 +35,6 @@ func idle(canGoIdle bool) {
 }

 type Game struct{
-		debug bool
 		x,y int
 		stepsPerFrame int
 		lastFrameDuration time.Duration
@ -60,23 +58,16 @@ func (g *Game) Update() error {
 	}
 	g.lastFrameDuration = time.Since(startTime)

-	if inpututil.IsKeyJustReleased(ebiten.KeyF12) {
-		g.debug = !g.debug
-	}
-
 	return nil
 }

 func (g *Game) Draw(screen *ebiten.Image) {
 	screen.DrawImage(framebuffer.framebuffer, nil)

-	if g.debug {
-		buf := fmt.Sprintf("PC: %08X FP: %08X RP: %08X ESP: %2X  %v",
-			cpu.PC, cpu.FP, cpu.RP, cpu.ESP, g.lastFrameDuration)
-		ebitenutil.DebugPrint(screen, buf)
-	}
-
 	/*
+	buf := fmt.Sprintf("PC: %08X FP: %08X RP: %08X ESP: %2X\n%v", cpu.PC, cpu.FP, cpu.RP, cpu.ESP, g.lastFrameDuration)
+	ebitenutil.DebugPrint(screen, buf)
+
 	screen.Set(g.x, g.y, color.RGBA{255,0,0,0})
 	screen.Set(g.x, g.y+1, color.RGBA{0,255,0,0})
 	screen.Set(g.x, g.y+2, color.RGBA{0,255,255,0})
--- a/utils/png2pict.py
+++ b/utils/png2pict.py
@ -2,9 +2,6 @@
 import sys
 import png

-sprite_width = 32
-sprite_height = 32
-
 def process_pixdata(outfile, pixdata, frameindex = 0, pix_w=640, pix_h=400):

    pixmask = 15
@ -31,22 +28,15 @@ def process_pixdata(outfile, pixdata, frameindex = 0, pix_w=640, pix_h=400):
            x += 8
        y += 1

-def write_palette_word(outfile, r, g, b):
-    r4 = r >> 4
-    g4 = g >> 4
-    b4 = b >> 4
-    c12 = r4 << 8 | g4 << 4 | b4
-
-    outfile.write(c12.to_bytes(4, 'big'))
-

 def process_palette(outfile, palette):
-    if len(palette[0]) == 4:
-        for r,g,b,a in palette:
-            write_palette_word(outfile, r, g, b)
-    else:
-        for r,g,b in palette:
-            write_palette_word(outfile, r, g, b)
+    for r,g,b in palette:
+        r4 = r >> 4
+        g4 = g >> 4
+        b4 = b >> 4
+        c12 = r4 << 8 | g4 << 4 | b4
+
+        outfile.write(c12.to_bytes(4, 'big'))


 def write_header(outfile):
@ -82,20 +72,22 @@ def write_pict_file(width, height, px, metadata, outfile):


 def write_sprite_file(width, height, px, metadata, outfile):
+    sprite_height=16
+
    print("processing as SPRT file with {} sprites...".format(height//sprite_height))
-    if width != sprite_width:
-        print("width must be {}, aborting".format(sprite_width))
+    if width != 16:
+        print("width must be 16, aborting")
        sys.exit(1)
    pixdata = list(px)
    palette = metadata['palette']

    if len(palette) != 16:
-        print("palette must have 16 colors instead of {}, aborting".format(len(palette)))
+        print("palette must have 16 colors, aborting")
        sys.exit(0)

    with open(outfile,'wb') as f:
        write_sprite_header(f)
-        process_pixdata(f, pixdata, pix_w=sprite_width, pix_h=height)
+        process_pixdata(f, pixdata, pix_w=16, pix_h=height)


 if __name__ == '__main__':
@ -111,8 +103,8 @@ if __name__ == '__main__':
    width, height, px, metadata = p
    if width == 640:
        write_pict_file(width, height, px, metadata, outfile)
-    elif width == sprite_width:
+    elif width == 16:
        write_sprite_file(width, height, px, metadata, outfile)
    else:
-        print("Can't handle this file, need a width of\n640 or {} pixels with 16 color palette.".format(sprite_width))
+        print("Can't handle this file, need a width of\n640 or 16 pixels with 16 color palette.")

--- a/utils/serload.py
+++ b/utils/serload.py
@ -16,7 +16,6 @@
 # limitations under the License.

 import sys
-import os
 import serial
 import time
 import random
@ -42,6 +41,30 @@ def get_default_device():
        return '/dev/ttyUSB1'


+def serwrite_slow(databytes, ser):
+    total = len(data)
+    count = 1
+    for d in data:
+        sys.stdout.write("writing {0:02x} {1:04d}/{2:04d}\r".format(ord(d), count, total))
+        ser.write(bytes(d,"utf8"))
+        count += 1
+        time.sleep(0.020)
+    print()
+
+
+def serwrite(datafile, ser):
+    with open(datafile) as f:
+        data = f.read()
+        total = len(data)
+        count = 1
+        for d in data:
+            sys.stdout.write("writing {0:02x} {1:04d}/{2:04d}\r".format(ord(d), count, total))
+            ser.write(bytes(d,"utf8"))
+            count += 1
+            time.sleep(0.020)
+        print()
+
+
 def checksum(databytes):
    i = 0
    cksum = 0
@ -62,26 +85,10 @@ def sendchar(char, ser):
    ser.write(char.to_bytes(1, 'big'))


-def sendcommand(ser, cmd=b'L', verbose=False):
-    verbose = True
+def sendcommand(ser, cmd=b'L'):
    ser.write(cmd)
    resp = ser.read_until()
-    if verbose:
-        print(cmd,"sent, response:", str(resp))
-    return resp
-
-
-# send command and wait for echo
-def commandwait(ser, cmd):
-    resp = sendcommand(ser, cmd, verbose=False)
-    if len(resp) == 0:
-        print("timeout sending '{}' command".format(cmd))
-        return None
-
-    if resp != bytearray(cmd + b"\r\n"):
-        print("invalid response to '{}' command".format(cmd))
-        return None
-
+    print(cmd,"sent, response:", str(resp))
    return resp


@ -146,8 +153,6 @@ def serload_bin(datafile, ser):

        data += bytearray(pad)

-    print("{} total blocks".format((len(data) + blocksize - 1) // blocksize))
-
    if not send_size_header(ser, filesize):
        print("Error sending size header.")
        return
@ -274,8 +279,18 @@ def serdownload(fname, ser):

 def mput(filenames, ser):
    for f in filenames:
-        resp = set_filename(f, ser)
-        if resp is None:
+        f_encoded = f.encode('utf8')
+        print("Setting filename", f)
+        resp = sendcommand(ser, b'S')
+        if len(resp) == 0:
+            print("timeout sending 'S' command")
+            return
+        if resp != b'S\r\n' and resp != b'> S\r\n':
+            print("unrecognized response to 'S' command, aborting")
+            return
+        resp = sendcommand(ser, f_encoded + b'\r')
+        if not f_encoded in resp:
+            print("unrecognized response to filename, aborting")
            return
        serload_bin(f, ser)

@ -284,92 +299,12 @@ def mput(filenames, ser):
        time.sleep(2)


-def set_filename(f, ser):
-    f_encoded = f.encode('utf8')
-    print("Setting filename", f)
-    resp = commandwait(ser, b'S')
-    if resp is None:
-        return None
-    resp = sendcommand(ser, f_encoded + b'\r')
-    if not f_encoded in resp:
-        print("unrecognized response to filename, aborting")
-        return None
-    return resp
-
-
-def getnamedfile(filename, ser):
-    resp = set_filename(filename, ser)
-    if resp is None:
-        return None
-    serdownload(filename, ser)
-
-
-def putnamedfile(filename, ser):
-    resp = set_filename(filename, ser)
-    if resp is None:
-        return None
-    serload_bin(filename, ser)
-    print("Remote status:")
-    showdata(ser)
-
-
-def showdata(ser):
-
-    promptseen = False
-
-    while not promptseen:
-        c = ser.read(1)
-        if c == b'>':
-            promptseen = True
-        else:
-            print(c.decode('utf8'), end='')
-    rest = ser.read(1)
-    
-
-def localdir():
-    result = os.walk(".")
-    for dirpath, dirnames, filenames in os.walk("."):
-        for f in filenames:
-            print(f)
-        break
-
-
-def interactive(ser):
-    done = False
-    while not done:
-        args = input("> ").strip().split()
-        if len(args) > 0:
-            cmd = args[0]
-            args.pop(0)
-            if cmd == 'dir':
-                if commandwait(ser, b'Y') is None:
-                    return
-                showdata(ser)
-            elif cmd == 'get':
-                if len(args) > 1:
-                    print("exactly one argument required (filename)")
-                else:
-                    getnamedfile(args[0], ser)
-            elif cmd == 'put':
-                if len(args) > 1:
-                    print("exactly one argument required (filename)")
-                else:
-                    putnamedfile(args[0], ser)
-            elif cmd == 'ldir':
-                if len(args) > 0:
-                    print("superfluous argument")
-                else:
-                    localdir()
-            else:
-                print("Unknown command. Valid commands are: dir get ldir put")
-                
-
 if __name__ == "__main__":
    argparser = argparse.ArgumentParser(
        description='transfer files from/to the Tridora-CPU')
    argparser.add_argument('-d', '--device', help='serial device', default=get_default_device())
-    argparser.add_argument('command', choices=['get', 'put', 'mput', 'interactive'])
-    argparser.add_argument('filename', nargs='*')
+    argparser.add_argument('command', choices=['get', 'put', 'mput'])
+    argparser.add_argument('filename', nargs='+')
    args = argparser.parse_args()

    cmd = args.command
@ -384,10 +319,8 @@ if __name__ == "__main__":
        serload_bin(filenames[0], ser)
    elif cmd == 'mput':
        mput(filenames, ser)
-    elif cmd == 'interactive':
-        interactive(ser)
    else:
        print("should not get here")

-    #if cmd is not None:
-    #    ser.close()
+    if cmd is not None:
+        ser.close()
--- a/utils/tdrimg.py
+++ b/utils/tdrimg.py
@ -535,11 +535,6 @@ def create_image_with_stuff(imgfile):
    slotnr = putfile("../progs/editor.pas", None , f, part, partstart, slotnr)
    slotnr = putfile("../progs/editor.prog", None , f, part, partstart, slotnr)
    slotnr = putfile("../progs/xfer.prog", None , f, part, partstart, slotnr)
-    slotnr = putfile("../progs/recover.prog", None , f, part, partstart, slotnr)
-    slotnr = putfile("../progs/changemem.prog", None , f, part, partstart, slotnr)
-
-    slotnr = putfile("../lib/pcmaudio.s", None , f, part, partstart, slotnr)
-    slotnr = putfile("../lib/pcmaudio.inc", None , f, part, partstart, slotnr)

    listdir(f, part)

@ -588,13 +583,16 @@ def create_image_with_stuff(imgfile):
    slotnr = putfile("../tests/test133.pas", None , f, part, partstart, slotnr)
    # slotnr = putfile("../tests/test133.prog", None , f, part, partstart, slotnr)

-    # slotnr = putfile("../tests/test159.pas", None , f, part, partstart, slotnr)
+    slotnr = putfile("../tests/test159.pas", None , f, part, partstart, slotnr)
    # slotnr = putfile("../tests/test159.prog", None , f, part, partstart, slotnr)

    slotnr = putfile("../tests/umlaut.pas", None , f, part, partstart, slotnr)

    slotnr = putfile("../examples/rtpair.pas", None , f, part, partstart, slotnr)

+    slotnr = putfile("../examples/5cubes.pas", None , f, part, partstart, slotnr)
+    # slotnr = putfile("../examples/5cubes.prog", None , f, part, partstart, slotnr)
+
    slotnr = putfile("../examples/3dcube.pas", None , f, part, partstart, slotnr)

    slotnr = putfile("../examples/conway.pas", None , f, part, partstart, slotnr)
@ -603,23 +601,13 @@ def create_image_with_stuff(imgfile):

    slotnr = putfile("../examples/lines.pas", None , f, part, partstart, slotnr)

-    slotnr = putfile("../examples/pcmtest2.pas", None , f, part, partstart, slotnr)
-
    slotnr = putfile("../examples/pictviewer.pas", None , f, part, partstart, slotnr)
-    slotnr = putfile("../examples/Toco_Toucan.pict", None , f, part, partstart, slotnr)
-    slotnr = putfile("../examples/shinkansen.pict", None , f, part, partstart, slotnr)
-    slotnr = putfile("../examples/snow_leopard.pict", None , f, part, partstart, slotnr)
-    slotnr = putfile("../examples/ADDS-Envoy-620.pict", None , f, part, partstart, slotnr)
+    slotnr = putfile("../examples/ara.pict", "ara.pict" , f, part, partstart, slotnr)
+    slotnr = putfile("../examples/shinkansen.pict", "shinkansen.pict" , f, part, partstart, slotnr)
+    slotnr = putfile("../examples/snow_leopard.pict", "snow_leopard.pict" , f, part, partstart, slotnr)

    slotnr = putfile("../examples/benchmarks.pas", None , f, part, partstart, slotnr)

-    slotnr = putfile("../examples/animate.pas", None , f, part, partstart, slotnr)
-    slotnr = putfile("../examples/sprites.inc", None , f, part, partstart, slotnr)
-    slotnr = putfile("../examples/sprites.s", None , f, part, partstart, slotnr)
-    slotnr = putfile("../examples/background.pict", None , f, part, partstart, slotnr)
-    slotnr = putfile("../examples/walking.sprt", None , f, part, partstart, slotnr)
-    slotnr = putfile("../examples/rocket.sprt", None , f, part, partstart, slotnr)
-
    listdir(f, part)

    part, partstart, slotnr = initfs(f, 5)
--- a/utils/wav2tdrau.py
+++ b/utils/wav2tdrau.py
@ -1,29 +0,0 @@
-import sys
-import random, struct
-import wave
-
-freq = 16000
-BIAS = 32768
-def convert(srcpath, destpath):
-	outdata = bytearray()
-	with wave.open(srcpath, mode="rb") as f:
-		params = f.getparams()
-		print(params.nchannels, params.sampwidth, params.framerate)
-
-		frames = f.readframes(2*1024*1024)
-		for i in range(0, len(frames), 2):
-			v = int.from_bytes(frames[i:i+2], "little", signed=True)
-			v += BIAS
-			hi = (v & 0xFF00) >> 8
-			lo = (v & 0x00FF)
-			outdata.append(hi)
-			outdata.append(lo)
-
-	with open(destpath, mode="wb") as f:
-		f.write(outdata)
-
-
-if __name__ == "__main__":
-	sourcefilename = sys.argv[1]
-	destfilename = sys.argv[2]
-	convert(sourcefilename, destfilename)