The veritable @porchy has created a new replacement for the Asteroids / Deluxe PROM (34602) at C8 using a GAL22v10: http://wiki.pldarchive.co.uk/index.php?title=Asteroids
The PROM at C8 is a 82S129 or compatible that runs the vector state machine. These PROMs are getting increasingly harder to source, expensive, and the hardware required to program them is no longer readily availble. There are existing alternatives such as a small pin converter board and a fast 27c256/512 EPROM, but there are many merits in using a GAL instead of these. GAL22v10 are still relatively cheap & plentiful (as of mid 2022), can be programmed with a MiniPro/TL866, come in a narrow 0.3" form-factor, and are pin-compatible (granted with some over-hang).
Burn the JED file to the GAL, solder a wire from pin 8 to pin 12 and place in a socket at C8 (let the trailing 8 pins hang out of the rear of the socket). Job done.
Nes4life2022-05-17 14:52:15
The PROM at C8 is a 82S129 or compatible that runs the vector state machine. These PROMs are getting increasingly harder to source, expensive, and the hardware required to program them is no longer readily availble. There are existing alternatives such as a small pin converter board and a fast 27c256/512 EPROM, but there are many merits in using a GAL instead of these. GAL22v10 are still relatively cheap & plentiful (as of mid 2022), can be programmed with a MiniPro/TL866, come in a narrow 0.3" form-factor, and are pin-compatible (granted with some over-hang).
Burn the JED file to the GAL, solder a wire from pin 8 to pin 12 and place in a socket at C8 (let the trailing 8 pins hang out of the rear of the socket). Job done.
Nes4life2022-05-17 14:52:15
