1c3d1v3r / neatrom

neatROM is a replacement circuit for 24 & 28 pin 8bit ROMs used in retro computers etc.

neatROM

neatROM is a replacement circuit for 24 & 28 pin 8bit ROM ICs used in retro computers.
The idea was to have a neat design like my other projects neatPLA, neat8701 & neatSRAM. All components are on the bottom side.

The 24pin version is called neatROM 2364. It supports:

• Use like a generic 2332 or 2364 replacement ROM.
• 16 jumper selectable 4/8kB banks.
• CS signal to pin 20. Also supports CS2 signal to pin 21 in VIC-20 character ROM mode.
• Reprogrammable with an adapter.
• Switchless Kernal Selector for VIC-20 & C64. Switch between two different Kernals with the Restore-key. Third Kernal selectable with a jumper.
• multiROM feature. Use only one neatROM 2364 in a C64 or VIC20 and replace missing ROMs with a connection to the missing ROM CS signal. In a long motherboard C64 one neatROM 2364 can replace all 3 ROMs (Basic, Kernal, Character). In VIC-20 one neatROM 2364 can replace both Kernal & Basic ROMS.

The 28pin version is called neatROM 23256. It supports:

• Use like a generic 2764, 23128 or 23256 replacement ROM.
• 8 jumper selectable 16kB banks or 4 jumper selectable 32kB banks.
• CS signal to pin 22.
• Reprogrammable with an adapter.
• Switchless Kernal Selector for C64 & C128. Switch between two different Kernals with the Restore-key.
• multiROM feature. Use only one neatROM 23256 in a short motherboard C64 and replace missing character ROM with a connection to the character ROM CS signal. Usage in C128 is under study.

Other information

neatROM PDF guide
neatROM Programming Adapter
ROM & Flash images

Licence

neatROM by Pasi Lassila is licensed under CC BY-SA 4.0