The board itself plugs into an EPROM socket on the main board. It carries a pass-through socket for the EPROM plus a set of LEDs and drivers.
The LEDs are driven from the address lines, which obvs are available from the EPROM pins.
The EPROM contains the soak test code. If it discovers an error it goes into a deliberate tight loop at a known location which can therefore be read off the LEDs, thus giving the error number.
Tim Ward ⭐🇪🇺🔶 #FBPE
npub17t…uq7ve
2025-04-30 16:34:14 UTC
in reply to nevent1q…f377
Author Public Key
npub17tv294uql48gtq8g8p2rtny4v7yvuf3krzcuflpja5t6hwhc5t9quuq7vePublished at
2025-04-30 16:34:14 UTCEvent JSON
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"content": "The board itself plugs into an EPROM socket on the main board. It carries a pass-through socket for the EPROM plus a set of LEDs and drivers.\n\nThe LEDs are driven from the address lines, which obvs are available from the EPROM pins.\n\nThe EPROM contains the soak test code. If it discovers an error it goes into a deliberate tight loop at a known location which can therefore be read off the LEDs, thus giving the error number.",
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