Custom ZX Spectrum +2A BIOS Project

This project implements a custom BIOS for the ZX Spectrum +2A, written in Z80 assembly language.

Overview

The BIOS provides fundamental system initialization and character display functionality, including a complete ZX Spectrum-compatible character set. It's designed to be assembled using the z80asm assembler.

Features

• System initialization
• Screen clearing and border color setting
• Complete ZX Spectrum character set implementation (space to ~, ASCII 32-126)
• Basic character printing routines

File Structure

• src/bios.asm: Main BIOS source code
• Makefile: Build automation
• bios.rom: Assembled BIOS ROM file (generated)

Building

To assemble the BIOS, ensure you have z80asm installed, then run:

make

This will generate the bios.rom file.

To clean up build artifacts:

make clean

Usage

The assembled bios.rom file can be used with ZX Spectrum +2A emulators or potentially on real hardware. When run, it initializes the system and displays all available characters on the screen.

Character Set

The BIOS includes a custom 8x8 pixel font covering the full printable ASCII range (32-126), including:

• Uppercase letters (A-Z)
• Lowercase letters (a-z)
• Digits (0-9)
• Punctuation and special characters

The character set is designed to match the ZX Spectrum's original font.

Contributing

Contributions to improve or extend this BIOS are welcome. Please feel free to submit issues or pull requests.

License

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

Acknowledgements

This project is inspired by the original ZX Spectrum +2A system and is intended for educational and hobby purposes.