StarJay Fantasy Console

Note: The public repo is 30 days behind the private development repo in order to provide a perk for patrons. This repo has active ongoing work, it just won't appear here for 30 days. If you would like to support development and get access to the latest code, please consider becoming a patron.

StarJay is a 16-bit era fantasy console with a focus on understandability. The goal is to provide the resources and interfaces required to fully understand the system and how it works, including detailed manuals, circuit schematics and a debug GUI.

Prerequisites / Dependencies

Install customasm from here: https://github.com/hlorenzi/customasm

If you have rust installed, this can be as simple as:

cargo install customasm

You also need zig installed. See https://ziglang.org/download/, 0.15.x is required until all dependecies support 0.16.x.

Building

zig build

Running Tests

make all
zig build test

Sieve of Eratosthenes Example

make examples
zig build run -- --rom starjette/examples/sieve.bin --debugger

Running a ROM with built-in debugger UI

You can build a rom for assembly with:

customasm -f binary -o <rom.bin> starjette/customasm/cpudef.asm starjette/customasm/test_kernel.asm <rom.asm>

zig build run -- --rom <rom.bin> --debugger

Running RISC-V

There is a RISC-V emulator included, activated with the --riscv flag:

zig build run -- --riscv --rom <riscv_rom.bin> 

Running the VDP Demo

You can run the VDP demo using the included RISC-V support:

cd riscv/examples/vdp_demo && zig build && cd ../../../
zig build run --release=safe -- --riscv --vdp --rom riscv/examples/vdp_demo/zig-out/bin/vdp_demo.bin

Running Linux

You can run a minimal Linux system using the included RISC-V support:

make dllinux
zig build run --release=safe -- --riscv --rom LinuxImage

License and Copyright

Copyright (c) 2026 Ryan "rj45" Sanche

This project is licensed under the MIT License - see the LICENSE file for details.