ti-emu: ROM FAIL in TI-85 emulator & other notes

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ti-emu: ROM FAIL in TI-85 emulator & other notes

Okay, I finally subscribed to the ti-emulator mailing list (something I
should have done a while ago). Browsing the archive, I saw some messages
noting that the self test reports "ROM FAIL". This is because the DUMP_ROM
program skips the last byte of each of the 8 pages in the TI-85's ROM. You
must change the last byte in each page (or the end of each 16384 block if
you already concatenated them) to 0xFF. The last byte of the last page is an
exception; it must be an "anti-checksum", or sort of a "checksum adjuster".
When you add together *all* the bytes in a ROM dump, the sum should be 0x00.
The self test checks to see if the checksum actually is 0x00, and if it
isn't it says "ROM FAIL".


Here are the anti-checksums (in hex):


ROM 2.0   - 2A
ROM 3.0A  - 57
ROM 4.0   - 8E
ROM 5.0   - 5E
ROM 6.0   - 3D
ROM 8.0   - 97
ROM 9.0   - 91
ROM 10.0  - 35


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David Ellsworth
the ticalc.org project
davidell@ticalc.org
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