Overscore

Overscore is a from-scratch CPU emulator, instruction set, assembler, and high-level programming language. It's an entirely separate computer ecosystem, starting from the ground up.

A little more detail for the CPU, emulator, assembler, and language:

• The CPU is a simple 32-bit CPU with 8 bit minimum addressable size and a small instruction set designed from scratch, but with several variants per instruction.
• The emulator emulates the behaviour of instructions from the instruction set. It handles 390 million instructions per second on my machine.
• The assembler converts readable assembly directly into bytes and machine code, with a few higher level constructs.
• The language is a tokenizer, parser, interpreter, and compiler, all in one. It's the most complex part of this project by far.

Overscore serves as a modern look into the hardware and software ecosystem if it were designed by a college freshman in 2025 (because it was). It's both an experiment with what improvements can be made by designing everything from scratch with a philosophy of simplicity in mind, as well as a learning project.

This is primarily a solo project, but if there are any questions (like "How do I run this myself?"), suggestions, or just general thoughts (maybe even some ideas for CPUs, instruction sets, or programming languages that you've had on your own that you want to share!), feel free to open an issue or contact me otherwise! I do follow the Zig philosophy of having a single individual with a dedicated vision for this project, though.

CPU

The CPU is a simple 32-bit CPU with 8 bit minimum addressable size and a small instruction set, with 8 core instructions and 19 instructions in total.

Extensive documentation for the CPU exists in CPU.md.

Assembly

The assembler provides a simple text-based way to write machine code, with a few higher level features.

Here's an example program. Documentation for the assembly can be found in ASSEMBLY.md.

raw Main

label Main
    mov10 100 AA
    mov11 104 100
    not1  104
    and11 100 104
    end

Language

The language is a work in progress. Documentation will be added soon.

Roadmap

A roadmap for the project exists in ROADMAP.md. It addresses several ideas and proposals for the project, mainly centering on the CPU, ISA, and assembler because the language is an incredibly complicated (and work-in-progress) part on its own.