Uxn-Logisim
Implements the Uxn instruction set in digital hardware. Very WIP.
Contents
- cpu.circ - The Logisim file
- microcode.mc - Microcode source file
- microcode-asm.py - Microcode assembler
- opcodes.py - Definitions for where opcodes live in the microcode ROM
Known Bugs
- The program counter doesn't reset to 0x0100
- To fix this, hold down the Reset button attached to the program counter and press Ctrl-T twice to advance the clock. This should set it to 0x0100 and program execution can begin.
- If your ROM contains absolute addressing then you'll need to manualy zero-pad it to start at 0x0100
cat /dev/zero | head -c 256 > zero-page.rom cat zero-page.rom someprogram.rom > padded-program.rom
- SFT isn't implemented
- ROT2/ROT2k are unimplemented
- Probably a lot of other opcodes don't work either
Quickstart
-
Open
cpu.circ
in Logisim -
( Optional ) Build the latest microcode
i. To assemble the microcode rom file run
python microcode-asm.py microcode.mc microcode.tal uxnasm microcode.tal microcode.rom
ii. Right click on the ROM labelled
Microcode_ROM
iii. Load Image > Select microcode.rom > Select binary (big-endian)
-
Load the Uxn ROM you wish to load.
i. Right click on the 64K RAM module ii. Load Image > Select a UXN rom > Select binary (big-endian)
Microcode Format
TODO
Microcode Assembler
The microcode assembler is only a partial assembler and relies upon Uxntal assembly for the conversion to binary. It takes in a [format](Microcode Format) similar to tal, and outputs a valid .tal file (Including comments!). Requires uxnasm or asma.tal to assemble into the microcode rom.