AVG Replacement Overview
As part of my studies into retro arcade technology, I created replacement parts for the custom Atari AVG chip. Other people have created AVG replacements, but nobody has released their source code. There is documentation on the web about the internal structure of the AVG chip but it is not entirely correct. I created replacement components based on the Tempest hardware. I created two versions of the AVG hardware. One design is a CPLD replacement of the logic and is contained within a single integrated circuit. The other uses discrete TTL ICs and recreates the Tempest hardware. The design has been tested on all the Atari AVG games with no known issues.
AVG Replacement RepositoryThe CPLD version of the AVG chip has a status LED that changes state every 64 video frames.
AVG CPLD Pictures
AVG CPLD Schematic
AVG CPLD PCB Design
AVG CPLD Hardare Source
The Atmel CPLD source was designed with CUPL.
Atmel CPLD SourceThe TTL version has an expansion port so the AVG addressing can be increased to a full 16 bits.
AVG TTL Pictures
AVG TTL Schematic
The AVG TTL PCB was also designed KiCad. Note there are patch wires in the images above but the current PCB design fixes those issues.
AVG TTL PCB Source
AVG TTL PCB Design
