Re: A92: Rom dump?
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Re: A92: Rom dump?
A ROM dump is a dump of the rom. It is not general knowledge how the new
fargo backups work, but the old ones worked by a bug in the 92, not the
graphlink software. On the 92, the ram goes from $00000 to $1FFFF (unless you
expand your ram to 256k, in which case it's $00000 to $3FFFF). The way fargo
is generally explained as working is the old method, where a backup larger
than the ram was sent. By way of a bug in the 92, it wrote to ram addresses
such as $20000 which aren't in the ram, and they wrapped around. So $20000
was the same as $00000, but he could write to $20000 and not to $00000. The
beginning of ram stores the vector table, a list of pointers to routines in
rom or ram that are run when different events occur. He would put code in the
ram, and the address of the code in one of the vectors. This vector was
activated when the backup was done sending, and the machine code he had put in
the ram earlier was executed. Then fargo was on the calc. That's simpler
than the way it works now, so that's basically how we explain it. It's not a
bug in the graphlink software anyway, because all the link software that we
have written works with it too. Anyhow...a ROM dump is for use with an
emulator on a computer. The emulator basically is a program that can emulate
the LCD and ports of the 92, and also act like a 68000 processor. It can
execute the code in the rom, and use part of the computer's ram as the ti-92's
ram, so the computer acts like a ti-92. It is not useful for many things, but
it is very useful for a few. It makes it easy to run programs you download
before you put them on your 92, so you can test them. For me, it's an
indespensible tool for debugging fargo programs. Reinstalling fargo on a calc
takes a few minutes, and would be a pain if I had to do it everytime I had an
address error or such in a fargo program I was writing. With the emulator,
all I do is run it, install fargo once, copy the file ti92.mem to backup.mem,
then whenever the emulator crashes, I overwrite ti92.mem with backup.mem. Rom
dumps will not be found on ti.com or ticalc.org, because the rom is property
of TI, and it's illegal to have a rom on your computer of a calc other than
one you own. There are twelve rom versions of the 92, so you can't just have
get a rom dump from anyone. If your calc is 1.12 and someone has a 1.11 rom
dump, you can't use that. The easiest way to make a rom dump is using a
parallel link. The graphlink method is much more complicated and error prone.
It took me four tries with the graphlink to get it right, and each try takes
20 minutes on a rom 1.x calc. 80 minutes...long time ;-) The parallel link
takes only a few minutes. I hope this cleared it up for everyone.