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 on the CPU architecture, 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 based on x86, RISC-V, and ForwardCom.
• The emulator simulates the behaviour of instructions from the instruction set. It handles 400 million instructions per second (MIPS) on my machine.
• The assembler converts readable assembly (Intel syntax) directly into machine code, with a few high-level constructs.
• The language is a relatively low-level language with inspiration from low-level languages like Zig, historical languages like BLISS, and functional languages.

Overscore serves as a somewhat modern but primarily opinionated look into the hardware and software ecosystem. It's both an experiment with what improvements (in my view) can be made by designing everything (yes, everything) from scratch with a philosophy of simplicity in mind. It's also 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, so some features exist for the sole reason that I have faith in them.

Usage

Overscore now supports usage as a CLI app! To install, simply run the following:

# Clone the repository
git clone https://github.com/GoldenStack/overscore.git
cd overscore

# Build the all-in-one binary (requires a Zig installation)
# Optionally add --release=fast for a faster binary!
zig build

# Use the built binary - run the help command to see what you can do!
./zig-out/bin/overscore help

Examples

Here are some examples, assuming you're in the project root and that the output binary is in path as overscore:

overscore assemble src/fibonacci.asm | overscore emulate

overscore interpret src/example2.os

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 22 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.

word Main

label Main:
    mov [#100x] #AAx
    mov [#104x] [#100x]
    not [#104x]
    and [#100x] [#104x]
    end

Language

The language is a work in progress. Documentation will be added soon, but for now you can take a look at the rationale which exposes several features of the language.

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.