Fixing a 3/80 NVRAM IDPROM

Use the following at your own risk. All numbers in hex.

Hit L1-Aafter you turn it on.
Comment: ^t is a command. Don't try control-T.

> ^t fef04000

you'll get output which includes the following (samples included)

TIA entry = 33FA500
TIB entry = 33FB80A
PTE = 64000049
Write these values down!!!

now change the TIA entry for fedfa000 to match the above

> m a fedfa000
TIA MAP FEDFA000 [...] ? 33FA500
hit control-D at next ? prompt

now change the TIB entry to match the above

> m b fedfa000
TIB MAP FEDFA000 [...] ? 33FB80A
now change the pagemap entry to match the above
> p fedfa000
PageMap FEDFA000 [...] ? 64000049

> o fedfa7d8 
.... now enter new IDPROM values. You need to get the checksum right. If you don't, you still won't be able to boot.

byte          contents
fedfa7d8      01    - version number - always 01
fedfa7d9      first byte of hostid (system type, 42 for sun 3/80)
fedfa7da-df   6 byte ethernet address (first three bytes are 08,00,20)
fedfa7e0-e3   date of manufacture. Often all 0s
fedfa7e4      second byte of hostid
fedfa7e5      third byte of hostid
fedfa7e6      fourth byte of hostid
fedfa7e7      idprom checksum  - xor of contents of bytes d8-e6
Click here to get the values calculated.
I don't know the original author of this Text but I tried this way of fixing a 3/80 several times and I can say it works :)