pawlos / timex.emu

An attempt to write a Timex 2048 emulator in python.

Timex.Emu

Timex.Emu is an emulator for a popular Timex 2048 machine.

Folder structure:

docs:

• Z80 CPU Manual
• Z80 CPU Peripherals
• Complete ROM

python:

• timex.py - main entry to the emulator

rom:

• Binary file containing ROM of actual machine

tests:

• a suite of unit tests
  • running tests: python3 -m unittest discover.

Links

• http://pl.wikipedia.org/wiki/Zilog_Z80
• http://pl.wikipedia.org/wiki/Timex_Sinclair_2048
• http://en.wikipedia.org/wiki/Timex_Computer_2048
• http://clrhome.org/table/

timex.emu's Issues

Support running ZEXALL tests suite

Based on https://floooh.github.io/2016/07/12/z80-rust-ms1.html

• the CPU emulator, attached to 64 KByte of empty, flat memory
• a raw dump of the ZEXALL or ZEXDOC Z80 binary code which must be loaded at address 0x0100 into the emulated RAM (this is where CP/M programs usually are located)
• set the CPU’s PC register (program counter, or instruction pointer) to the program start at 0x0100, and the stack pointer to 0xF000 (I have no idea where the stack pointer is in CP/M, it just has to be in an area that’s not overwritten while the test runs)
• start executing instructions… this will properly update the CPU state, but we can’t see anything from the outside…
• at some point, the code will call into CP/M operating system functions by jumping to address 0x0005, with a number in register C that identifies the requested function. Thankfully ZEX only calls 2 different functions, one is 0x02 which outputs a single character to the terminal, and the other is 0x09, which outputs a string (terminated by the character ‘$’, not a null byte)

So to emulate the required CP/M calls I need to:

• after each instruction, check whether the PC register is 0x0005
• if the C register is 2, output the value in register E as ASCII code to the console
• if the C register is 9, start reading bytes at the address in register pair DE until ‘$’ and output them as ASCII to the console

16-Bit Load Group

Page: 102

Additional tests for flags changes

• changes in flags needs to be verified in order for CPU to work correctly

Allow debugger to respond to commands

it should be possible to print registers, memory data, etc

Organize tests better

Split up tests into multiple files. Tests should be moved into python folder as they written are in python

Organize CPU

split CPU into modules

Implement XOR flags setting

um0080.pdf:157

Extract logger to separate class

Display

Currently there's no way to display anything if screen buffer is populated with data. There should be a way to display drawing on screen.