# Macrosilicon Custom Firmware: rebuilding USB video chip EEPROM firmware

> Macrosilicon Custom Firmware studies the 8051 mask ROM and EEPROM loading behavior of MS2107, MS2109 and MS9123 USB video chips, then builds replacement EEPROM images. Its chip notes map hooks, headers and memory addresses; host tools dump device memory and access new HID mailbox commands for status, GPIO and I2C.

- Type: Case study
- Targets: Firmware
- Category: Independent reconstruction cases
- Relationship: Independent reconstruction project
- Sources reviewed: 2026-11-08
- Added to the catalog: 2026-11-09
- Original resource: <https://github.com/kraln/macrosilicon_firmware>
- Primary source: <https://github.com/kraln/macrosilicon_firmware/blob/caa3d270fd656858a5b004c5498fe03a52c57e5f/README.md>
- Catalog page: <https://awesomerea.org/resources/macrosilicon-custom-firmware-case/>
- Record JSON: <https://awesomerea.org/resources/macrosilicon-custom-firmware-case/record.json>
- Chinese version: [简体中文](https://awesomerea.org/zh/resources/macrosilicon-custom-firmware-case/index.md)

## Requirements & limits

- **Prerequisites:** A supported MS2107, MS2109 or MS9123 device; build instructions use SDCC tooling.
- **Testing evidence:** The MS2109 D7 mailbox has been tested from RAM, but its flashed image has not been run on hardware.
- **License:** No licence file in the repository.

## Primary sources

1. <https://github.com/kraln/macrosilicon_firmware/blob/caa3d270fd656858a5b004c5498fe03a52c57e5f/README.md>
2. <https://github.com/kraln/macrosilicon_firmware/blob/caa3d270fd656858a5b004c5498fe03a52c57e5f/ms2109/rom/d7_rom_notes.md>
3. <https://github.com/kraln/macrosilicon_firmware/blob/caa3d270fd656858a5b004c5498fe03a52c57e5f/docs/macrosilicon-notes.md>

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## About this entry

The description was reviewed against primary sources.
Original editorial content: MIT. Linked projects, papers and assets retain their own rights and licenses.