Nels Bruckner wrote:
> On Sep 6, 2:33 pm, Linards Ticmanis <ticma...@gmx.de> wrote:
>> Nels Bruckner wrote:
>>> The next thing I could try is swapping in a second set of ROM 3 ROM
>>> chips, which I don't have. My usualy saviors in this kind of
>>> situation, Reactive Micro, don't seem to carry ROM 3 replacements.
>>> Any suggestions?
>> On an 8-bit Apple I'd just write and run a quick Applesoft program to
>> checksum the ROM (sum or EOR of all bytes), test it on an emulator and
>> on the real system and see if the results differ.
>> I don't know the IIgs well enough to know whether the entire ROM is
>> readable from Applesoft. You might need assembly, but I assume it would
>> be short enough to just enter from the CALL -151 monitor.
>> --
>> Linards Ticmanis
> Could certainly do that, but whether pass or fail it wouldn't
> give me much new info.
Actually, it will verify whether your machine is reading its ROM
correctly, which is an issue.
> I did discover that the application failures I was seeing were
> because (duh) I hadn't installed a RAM card in this machine. Now that
> the machine has 2MB of RAM it runs Dungeon Master, etc, just fine.
> Which really just leaves me with the curious fact that the diagnostic
> software reports a failure of the CPU/ROM validation step, since the
> machine seems to function just fine.
It's not hard to imagine a fault which the software you have tried
does not "exercise", or which it tolerates.
CPU/ROM validation must be very early in the self-test sequence, so
most of the test may not even be running.
> I'm keeping my eyes open for a
> second, dirt cheap ROM 3 machine (I think I got this one for $20+p/h)
> to swap ROMS with but, in the meantime, anyone know where I can pick
> up a set of ROM 3 chips?
Running the checksum that Linards suggested, and comparing it with
the same test run on an emulator configured for ROM 3 will answer
the question of whether or not the ROM is bad.
Swapping the processor is just as easy as swapping the ROM, and
you can use any version of a IIgs for the swap.
-michael
AppleCrate II: An Apple II "blade server"!
Home page: http://members.aol.com/MJMahon/
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