# Beavis Ultrasound PnP ISA Sound Card Replica Open-source replica of Gravis Ultrasound PnP with design details. - **Source:** [Hacker News (news.ycombinator.com)](https://brifing.si/source/13c923cd-6d99-442b-9b8b-1181f4d8cd91) - **Published:** 2026-07-13 - **Topic:** [Software & Engineering](https://brifing.si/c/engineering) - **Original article:** - **On Brifing:** https://brifing.si/s/4ee18305-cf07-4bee-adc9-94d1d36cac1b ## Retro Sound Card Clone The Beavis Ultrasound PnP ISA is an open-source replica of Gravis Ultrasound PnP. The design includes schematics and reverse-engineered GAL source code. It provides basic sound card functionality using an AMD InterWave chip. ## Hardware Specifications The board measures 8.2 x 4.2 inches with 4 layers. ENIG plating suffices for edge connectors. The AMD78C201 chip handles all audio functions, while optional GAL programming enables IDE support. ## Assembly Notes Low-noise op-amps like LM833 or JRC5532 can be used. Ferrite beads can be replaced with 0-ohm resistors. Test pads JPR12/JPR13 are omitted, and the unused PLL chip (U100) remains non-functional in the design. ## Programmable Components The 1MB sample ROM (IW78C21M1) can be replaced with a programmed 27C800 chip. The 93C66 EEPROM requires bit-order reversal when programming. The GAL chip is essential for IDE functionality. ## Design Limitations No fabrication package has been created, and the board remains untested. Users build at their own risk. Isolation cuts in analog/digital power planes reduce crosstalk between supplies. ## Retro Hardware Legacy This project preserves historic sound card technology while offering customizable open-source solutions. It serves as a technically detailed reference for electronics enthusiasts. ## Sources covering this story - https://github.com/schlae/BeavisUltrasound — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._