# Beavis Ultrasound PnP ISA Sound Card Replica An open-source replica of the Gravis Ultrasound PnP - **Source:** [Hacker News: Front Page](https://brifing.si/source/b07aa772-b1a0-4a76-aa18-719c6f9e2dde) - **Published:** 2026-07-13 - **Topic:** [Software & Engineering](https://brifing.si/c/engineering) - **Original article:** - **On Brifing:** https://brifing.si/s/807b60ec-a875-4587-8f9b-68d27d85a839 ## Beavis Ultrasound PnP ISA Sound Card Replica The Beavis Ultrasound PnP ISA Sound Card Replica is an open-source copy of the Gravis Ultrasound PnP. This design includes the reverse-engineered source code of the GAL and the complete schematic. Developed using the AMD InterWave chip, the card integrates all sound card functions into a single chip. ## Design and Production The card's design is quite simple as all sound card functions are provided by the AMD InterWave chip. The card measures 8.2 x 4.2 inches (208 x 107mm) and is 4 layers thick. ENIG plating can be used in the production process, although hard gold, technically superior, is prohibitively expensive. ## Assembly Notes Dual op amps can be substituted. While the BOM specifies LM833, JRC5532 can also be used. Essentially, any ~10MHz low-noise op amp that can handle a +/-8V input power supply will suffice. If ferrite beads are missing, they can be replaced with a 0 ohm resistor or a piece of wire. ## Programmable Devices U8, the IW78C21M1, is the 1MB sample ROM. If this chip is unavailable, the sample ROM can be downloaded from the internet and burned onto a 27C800. U6/U60, the 93C66 EEPROM, contains the plug-and-play configuration data and should be programmed with the contents of ultrasound_pnp.bin. ## GAL Usage U14, the GAL, is used for various purposes such as buffering IOCS16 from the IDE port to the ISA bus, buffering the bus reset signal to the IDE port, and decoding some address lines. If the CDROM IDE function is not needed, the GAL is unnecessary. ## Conclusion and Importance The Beavis Ultrasound PnP ISA Sound Card Replica is a significant project for reviving old technology and providing an open-source design. This card is a valuable resource for those interested in understanding the evolution of sound card technology and reproducing old hardware. ## 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._