• 3WIRE
  • Intermediate
  • 5 min
  • EEPROM shell

Recipe · Intermediate · 3WIRE

How to dump a 93Cxx Microwire EEPROM

3WIRE mode targets Microwire-style EEPROMs such as 93Cxx chips with CS, SK, DI and DO pins.

Microwire EEPROM connected to a three-wire bus.
The ORG pin matters: x8 and x16 organization change how the same chip is read.

Wiring View

93Cxx EEPROM BP CS3WIRE CSSK3WIRE SKDI3WIRE DIDO3WIRE DOGNDGND
Generated from the wiring summary: 93Cxx EEPROM to BP.
Step 1

Commands

eeprom opens the interactive shell. Select the model, answer the ORG question, then choose Probe and Dump EEPROM.

Result

What it means

A stable dump in the expected size means wiring and organization are likely correct. Two matching dumps are better than one.

Troubleshooting

  • ORG pin floating or tied to the wrong rail.
  • DI and DO swapped.
  • Target board still powering or driving the EEPROM.
  • Long clip wires causing intermittent reads.

Next steps

  • Repeat the dump and compare it.
  • Record chip marking, ORG state and supply voltage beside the dump.
  • Only use write or erase after you have a verified backup.

93Cxx EEPROM dump FAQ

Why does the ORG pin matter so much?

The ORG pin selects x8 or x16 organization on many 93Cxx EEPROMs. If it is floating or tied incorrectly, the dump size and byte order can look wrong even when wiring is otherwise correct.

How do I know the dump is trustworthy?

Make at least two dumps and compare them. A stable size and matching data across repeated reads are stronger evidence than a single successful probe.

Can I dump a 93Cxx chip in-circuit?

Sometimes, but the surrounding board may power the chip or drive CS, SK, DI or DO. For unreliable reads, isolate the chip or make sure the target circuit is not fighting the Bit Pirate.

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