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README.md

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+# Tridora System
+Tridora is a homebrew CPU written in Verilog and a matching software environment,
+including a Pascal compiler and assembler.
+Everything was created from the ground up (except soldering stuff).
+Everything is as simple as possible while still being reasonably useful.
+Everything is open source, so you can read, understand and modify the whole system, hardware and software.
+
+## Overview
+- Homebrew CPU
+- Verilog FPGA SoC
+- 32-bit word-oriented stack machine architecture
+- running at 83 MHz on an Arty-A7 board with four clocks per instruction
+- has its own instruction set architecture, compatible with nothing
+- additional IO controllers on FPGA: UART (serial console), SD-Card, VGA
+- Pascal compiler written from zero
+- CPU and compiler were designed together
+- minimal operating system
+- editor, compiler, assembler run natively
+- so you can develop programs directly on the machine
+- small: CPU has 760 lines of verilog, compiler ~9000 LoC
+- Compiler written in Pascal and can compile itself
+- Cross-compiler/-assembler can be compiled with FPC
+- Compiler does its own Pascal dialect with some restrictions and some extensions
+- Emulator available
+
+## Demo
+- (Video hello world)
+- (Video lines)
+- (Screenshot mandelbrot)
+- (Screenshot conway)
+- (Screenshot image viewer)
+
+## Supported Boards
+- Arty A7 (with two PMODs for microSD cards and VGA output)
+- Nexys A7 (not ready yet)
+
+## Pascal Language
+- Wirth Pascal
+- no function types/parameters
+- arbitrary length strings (2GB)
+- safe strings (runtime information about max/current size)
+- tiny sets (machine word sized), that means no SET OF CHAR
+- array literals with IN-operator, which can replace most uses of SET OF CHAR
+- nested procedures with some limitations
+- 32 bit software floating point with low precision (5-6 digits)
+- break and exit statements, no continue yet
+- static variable initialization for global variables
+- non-standard file i/o (because the standard sucks, obl. XKCD reference)
+
+## Standard Library
+- everything from Wirth Pascal
+- some things from TP3.0
+- some graphics functionality (to be expanded in the future)
+
+## Operating System
+- not a real operating system, more of a program loader
+- some assembly routines for I/O resident in memory
+- one program image loaded at a time at a fixed address
+- most parts of the operating system are contained in the program image
+- file system is very primitive: only contiguous blocks, no subdirectories
+- simple shell reminiscent of TP3.0, edit, compile, run programs