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[TorZidan]

I am playing with the various Lisa ROMs from http://www.bitsavers.org/bits/Apple/Lisa/firmware/ in the LisaEm emulator.
I tried Rom versions B,C,D and H.

For each Rom version, the emulator successfully produces a merged "boot.ROM" file (a rather obscured feature).

The emulator boots fine with Roms B and H.
However, when trying to boot C and D Roms, I get a popup error: "BOOT ROM checksum doesn't match, this may crash the emulator."  And indeed, it crashes (blank screen).

Is it possible that the C and D ROM images at http://www.bitsavers.org/bits/Apple/Lisa/firmware/  are indeed corrupted?
I can't find them anywhere else online.

At https://lisalist2.com/index.php/topic,80.msg393.html#msg393
Ray said that "D" Roms are best for use with Lisa 1, which makes me think that he (the LisaEm creator) was able to successfully boot a D rom in the emulator ...

Note: Here are the relevant LisaEm logs for Rom D:
src/lisa/cpu_board/rom.c:checkromchksum:248:Original Lisa ROM CHKSUM is 3358
src/lisa/cpu_board/rom.c:checkromchksum:249:Lisa ROM Checksum is e78f,negated it's ffff1871, zero=0000

[sigma7]

Is it possible that the C and D ROM images at http://www.bitsavers.org/bits/Apple/Lisa/firmware/  are indeed corrupted?

For both revs C & D, bitsaver's 341-0176 match what I have, but 341-0175 do not (but are close). Will try to figure out where the mixup is.

BTW, Rev D is recommended as the last revision contemporary with the Lisa 1, but I suspect later versions are still compatible.

[sigma7]

Summary of a non-rigorous investigation:

It looks like the eighth address bit of the eprom reader was unreliable.

The lines that have errors appear to be of the pattern:
when reading address 0A00 it actually read 0B00
when reading address 0E00 it actually read 0F00
etc.

The number of incorrectly read bytes is inconsistent.
At 0A00 there are 14 bad bytes
At 0A10 there is one bad byte

The files in question that I have were uploaded to https://lisalist2.com/index.php/topic,615.msg4335.html#msg4335

[TorZidan]

Hi sigma7,

I was able to assemble a good C rom using your file 341-0175REVC.bin.zip  and the file 341-0176-C.bin from Bitsavers. The checksum is just right and the  emulator boots it fine. Thank you!

About the D rom: merging the half D Rom you uploaded did not result into a healthy D rom. It does not pass the checksum, again.

[sigma7]

I was able to assemble a good C rom

Some progress is good!

I've double checked that the MD5 digest of bitsaver's and my Rev D 341-0176 match.

Not knowing where else to look, I've uploaded a merged D ROM; hopefully that will work, although it is certainly possible I have a bad file too.

[TorZidan]

Sigma7, your merged D Rom works great in the emulator.
I don't know why I wasn't able to do a successful merge myself.
I am all set. Thank you!

I hope other people interested in this stuff will be able to gather these bits of pieces of the puzzle...