Introduction

This device provides a high-speed USB interface between a PC and a Capcom CPS-2 board. I developed it for the purposes of data logging and to rapidly develop and test programs. It also had several of the video bus pins connected to an input buffer so the state of the sync outputs could be monitored by the software for interrupt-free screen synchronization.

Project status

The initial version had an incorrectly designed DTACK generator for the custom 68000 CPU. Luckily all the necessary signals went to the GAL which has enough internal memory to implement a shift register, and that was an ideal solution to generating the DTACK signal appropriately.

This was used to log large amounts of data (4 gigabytes each) from several CPS-2 games, which enabled analysis of the output from the decryption logic that is implemented in several ASICs on the ROM board. That led to the encryption scheme being figured out by Nicola Salmoria and Andreas Naive, and enabled many CPS-2 games to be fully decrypted and preserved. Even with fast transfer rates it still took hours and hours to get all that data, but having such positive results through the hard work of everyone involved made the effort well worth it.

The PCB layout also includes a 22V10 to 16V8 PAL adapter. This can be deleted to free up some more board space if necessary.

Files