Outrun Music Extender

Cmonkey and me worked on this project back in March 2015.
Cmonkey found that the new tunes added to the 3DS release of Outrun were in the same format as the original arcade. With that in mind he set about adding the tunes to his Outrun arcade PCB. He succeeded but the problem was there wasn’t enough room in the standard EPROM’s to add these alongside the existing music.
My contribution started here and found one of the pins of the PLD used to select chips was essentially unused so I could use this to switch the new music in and out. Cmonkey modified the code so that the gear shift lever switched in the new tunes.
I designed a PCB which will slot directly into the Z80 code EPROM socket on the Out Run board set. The PCB incorporates a PLCC32 socket and map the pins of a 28-pin 27512 EPROM to the equivalent pins of a PLCC32 memory (39SF010A or equivalent).

Original mock up of the PCB

Parts required for this are
1 x PLCC32 socket
1 x 1Mbit PLCC32 flash memory (39SF010A or equivalent)
4 x 27512 EPROM’s for the patched 68000 code
1 x GAL16V8 for new Z80 address decoding
2 x 14-way pin headers
1 flying wire to link the A16 point on the PCB to pin 18 of the GAL

Note: Pin 18 of the GAL needs to be removed from the socket in order to work