The below link shows the array of the two pairs. One pair is functioning. The malfunctioning chip, of the other pair, works for 1-2 seconds before manifesting bit rot distortion.
The questions I have before further pursuing this project.
The closest EPROM replacement I have found is M27C322-100F1 STMicroelectronics | Mouser United Kingdom , but the operating currents are not quite equivalent (Will this mean that a replacement is not feasible because a suitable EPROM replacement cannot be found?)
If the EPROM could be used... Which, if any, Arduino board would be most suitable for this task?
That EPROM can replace the 4 ROMS. Access time is only 100ns instead of 120ns (ROM). The max. current of one active pair of ROMS is 2*60mA while the EPROM consumes only 70mA. No problem so far
An Arduino is not required. You'll have to build an adapter that fits the EPROM pins into your ROM sockets or to the board. In 2MB16 you can store more than the 2512k28, so that you can program and select one of two sets of data.
Find a programming facility for the EPROM, that also can read your ROMs if possible. Good luck
DrDiettrich:
That EPROM can replace the 4 ROMS. Access time is only 100ns instead of 120ns (ROM). The max. current of one active pair of ROMS is 2*60mA while the EPROM consumes only 70mA. No problem so far
An Arduino is not required. You'll have to build an adapter that fits the EPROM pins into your ROM sockets or to the board. In 2MB16 you can store more than the 2512k28, so that you can program and select one of two sets of data.
Find a programming facility for the EPROM, that also can read your ROMs if possible. Good luck
Thanks for the quick reply and information. Am I correct in thinking you saying I will be able to use one EPROM to cover the pair of mask ROMs - As long as I can fabricate a sort of dual adaptor over the 2 mask Roms pin layout?
Right. In bytes the old ROMs have 512k each, 2MB in 2 pairs. The new EPROM has 2MB*2, enough for 2 sets of 2MB.
You still have to figure out whether the ROM pairs really feature a 16 bit data bus, so that the 16 bit of the EPROM are immediately usable.
Also figure out how the OE and CE pins are configured with the ROMs, a logic analyzer will be helpful. With the EPROM one of these signals has to be used as another "pair" address bit, another one for OE, the CE is optional.
Maybe i'm missing something here but if the malfunctioning device is a mask ROM, then where are you going to get uncorrupted data from to put into the replacement device?
EDIT: As this is a feasibility question, I would think it would be possible to recreate the malfunctioning device. You may have to mount the new device on an adapter board if the pinouts don't match.
markd833:
Maybe i'm missing something here but if the malfunctioning device is a mask ROM, then where are you going to get uncorrupted data from to put into the replacement device?
EDIT: As this is a feasibility question, I would think it would be possible to recreate the malfunctioning device. You may have to mount the new device on an adapter board if the pinouts don't match.
Yes without a working donor chip this project will be even more ridiculous - as I would have to reverse engineer the binaries, and code my own wave sounds. Something that I'd love to be able to do but a long way off...
My plan was to try to find a working chip- but I can at least extract half of the data and progress somewhat if it is feasible.
