4 ms·

The Nintendo PlayStation contains an undumped 4-bit NEC MCU for its CD controller. Once that EEPROM bit-rots (it's already past its guaranteed lifetime), the Su

by byuu 7y ago

The Nintendo PlayStation contains an undumped 4-bit NEC MCU for its CD controller. Once that EEPROM bit-rots (it's already past its guaranteed lifetime), the SuperDisc BIOS cartridge will no longer boot as-is. The two fan-made games ported to the CD-drive will no longer function at that point, and we won't ever be able to directly fix this, only to hack around and approximate the original functionality. I imagine this won't be a significant loss to its new owner, but it's still unfortunate.

sgrove 7y ago
Given your qualifications, what would you like to see happen?
- byuu 7y ago
  Find the most qualified engineer in the world to desolder the surface-mount MCU, read out its firmware using the documented debugging mode from the datasheet, and then resolder the MCU back to the system. It won't happen, but it would be nice for posterity.
  - numpad0 7y ago
    Test clips won’t work with it?
  - parski 7y ago
    I'd love for this to happen. Then have a MiSTer code made for it or something. Maybe a bsnes variation? A girl can dream.
garaetjjte 7y ago
What are the retention times for contemporary EPROMs? Datasheet for µPD75P308 doesn't seem to specify that. Modern EEPROMs specify retention time at over 100 years in room temperatures, shouldn't old chips be even safer due to older/larger process node?
ndiddy 7y ago
The MCU variant on the motherboard https://i.imgur.com/ehNHPeY.jpg https://i.imgur.com/ehNHPeY.jpg is one-time programmable, as opposed to an EPROM. Because of this, I wouldn't worry about it losing its data, as OTP ROMs use blown fuses to store 1/0 state. It's true that it could just be an EPROM without a window, but the datasheet mentions two different programmers, one for the EPROM variant and one for the OTP variant so I doubt this is the case. More information: https://pdf1.alldatasheet.com/datasheet-pdf/view/7077/NEC/UPD75P308GF-3B9.html https://pdf1.alldatasheet.com/datasheet-pdf/view/7077/NEC/UP...

by byuu 7y ago

sgrove 7y ago

Given your qualifications, what would you like to see happen?

byuu 7y ago
Find the most qualified engineer in the world to desolder the surface-mount MCU, read out its firmware using the documented debugging mode from the datasheet, and then resolder the MCU back to the system. It won't happen, but it would be nice for posterity.
- numpad0 7y ago
  Test clips won’t work with it?
- parski 7y ago
  I'd love for this to happen. Then have a MiSTer code made for it or something. Maybe a bsnes variation? A girl can dream.

garaetjjte 7y ago

What are the retention times for contemporary EPROMs? Datasheet for µPD75P308 doesn't seem to specify that. Modern EEPROMs specify retention time at over 100 years in room temperatures, shouldn't old chips be even safer due to older/larger process node?

ndiddy 7y ago

The MCU variant on the motherboard https://i.imgur.com/ehNHPeY.jpg https://i.imgur.com/ehNHPeY.jpg is one-time programmable, as opposed to an EPROM. Because of this, I wouldn't worry about it losing its data, as OTP ROMs use blown fuses to store 1/0 state. It's true that it could just be an EPROM without a window, but the datasheet mentions two different programmers, one for the EPROM variant and one for the OTP variant so I doubt this is the case. More information: https://pdf1.alldatasheet.com/datasheet-pdf/view/7077/NEC/UPD75P308GF-3B9.html https://pdf1.alldatasheet.com/datasheet-pdf/view/7077/NEC/UP...