AKAI S950 - dual ROM support

[pmoneynz]

I’m looking at replacing the ROMs in an Akai S950 sampler.

It has two MBM27C256 EPROMs arranged as a 16-bit byte-lane pair:

• shared address bus
• shared /CE
• shared /OE
• one ROM drives D0-D7
• the other drives D8-D15
• NEC μPD70116 (V30 family) CPU

Has anyone already used OneROM in this type of dual-byte-lane configuration?

Would you recommend:

• two Fire-28 boards,
• a different board,
• or is there existing support for paired byte-lane ROMs?

[piersfinlayson]

I remember the Akai samplers - I even sold a few in my time.

This should work just fine. I don't know if people have used the 8-bit ROMs in a 16-bit pair (I'm sure they will have), but people have used the 16-bit One ROMs in 32 bit pairs successfully.

I'd recommend 2 x Fire 28s. You'll obviously need to split the 16-bit image correctly to program each with the upper or lower half as the tooling doesn't currently support doing this itself yet.

The MBM27C256 is listed as both 200ns and 250ns access time parts. Either should be well within One ROM's capabilities.

[pmoneynz]

Brilliant. Thanks for the advice. I'll reply here with my results. Cheers