https://github.com/DeltaF1/uxn-logisim

Port of Uxn to digital hardware in the Logisim simulator
https://github.com/DeltaF1/uxn-logisim

Last synced: 3 months ago
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Port of Uxn to digital hardware in the Logisim simulator

• Host: GitHub
• URL: https://github.com/DeltaF1/uxn-logisim
• Owner: DeltaF1
• Created: 2021-11-02T03:37:48.000Z (about 3 years ago)
• Default Branch: main
• Last Pushed: 2023-12-11T19:06:07.000Z (11 months ago)
• Last Synced: 2024-05-21T08:32:03.736Z (6 months ago)
• Language: M4
• Size: 70.3 KB
• Stars: 13
• Watchers: 4
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

• awesome-uxn - Logisim - Incomplete. (Emulators)

README

        
# Uxn-Logisim

Implements the Uxn instruction set in digital hardware. Very WIP.

![An animation showing different Uxn mode bits lighting up as stack control signals flow through logic gates](splash.gif)

## Contents

* [cpu.circ](cpu.circ) - The Logisim file

* [microcode.mc](microcode.mc) - Microcode source file

* [microcode-asm.py](microcode-asm.py) - Microcode assembler

* [opcodes.py](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.

  - Alternatively, type a0 01 00 2c into the first four bytes of the zero-page to make the cpu jump to the start

  - If your ROM contains absolute addressing then you'll need to manualy zero-pad it to start at 0x0100

    ```sh

    cat /dev/zero | head -c 256 > zero-page.rom

    cat zero-page.rom someprogram.rom > padded-program.rom

    ```

## Quickstart

1. Open `cpu.circ` in Logisim

2. ( Optional ) Build the latest microcode

	

	i. To assemble the microcode rom file run

	```sh

	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)

3. 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.