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Update Unlock Ben Eater Hardware notes

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Tom Nisbet 2020-08-10 14:18:10 -04:00
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docs/28C256-notes.md
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@ -36,6 +36,10 @@ hand, will refuse to unlock when the timing is outside the acceptable maximum.
# Solution
**Note:** if you are using the Ben Eater EEPROM programmer, see the
[unlock-ben-eater-hardware sketch](https://github.com/TomNisbet/TommyPROM/tree/master/unlock-ben-eater-hardware)
for a solution to disable SDP on locked chips.
The TommyProm programmer uses direct port access on the Arduino to control the data bus
and addressing shift register. This is much faster than doing individual DigitalWrite
calls and allows the unlock and page write code to run comfortably within the tBLC

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unlock-ben-eater-hardware/README.md
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#Unlock Ben Eater Hardware
![Ben Eater EEPROM Programmer](../docs/images/ben-eater-hardware.jpg)
Utility to unlock 28C256 Software Data Protection (SDP) for the
[Ben Eater EEPROM](https://github.com/beneater/eeprom-programmer)
programmer design. This hardware is similar to the TommyPROM hardware, but it uses
different shift register chips and different pin assignments.
To meet the timing requirements of the SDP unlock, this code uses direct port writes
to set and read values on the data bus. It will work Arduino Uno and Nano hardware,
to set and read values on the data bus. It will work with Arduino Uno and Nano hardware,
but would require changes for other platforms.
**NOTE** that this sketch **will not** work on TommyPROM hardware. It is included here