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23 lines
1.0 KiB
Markdown
23 lines
1.0 KiB
Markdown
# Unlock Ben Eater Hardware
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Utility to unlock 28C256 Software Data Protection (SDP) for the
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[Ben Eater EEPROM](https://github.com/beneater/eeprom-programmer)
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programmer design. This hardware is similar to the TommyPROM hardware, but it uses
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different shift register chips and different pin assignments.
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To meet the
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[timing requirements of the SDP unlock](https://tomnisbet.github.io/TommyPROM/docs/28C256-notes),
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this code uses direct port writes
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to set and read values on the data bus. It will work with Arduino Uno and Nano hardware,
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but would require changes for other platforms.
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**NOTE** that this sketch **will not** work on TommyPROM hardware. It is included here
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to help people with locked chips who are using the Ben Eater design.
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The timing trace shows the tBLC for the bytes of the unlock sequence within 65us, well
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within the required 150us in the datasheet.
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