steve@dcdwest.UUCP (Steve Meloche) (12/15/89)
Hi. I am an Amiga 1000 owner (for three years) and my computer has
developed a problem. First, the background: my A1000 is a "refurbished" model
bought from M.C.S. (Note: I have bought three things from them and have had
prompt, reliable service every time). Within a year I had installed a 1 MB
Insider board from Michigan Software. Everything went great for about a year,
until one of the chips on the Insider board developed a bad bit, which caused
random gurus in previously reliable software. I isolated the problem with the
supplied memory test from Michigan Software and they fixed it free! (Well, I
had to pay shipping to them). Another year of great Amiga fun had gone by
when, this last Sunday Amy gurued while sitting at the "Insert Workbench Disk"
prompt, right after loading kickstart. Oh no, I said, not again! It rebooted
o.k., but started doing wierd things and guruing frequently. I have run
MD (memory diagnostic) and memtest, but neither of these has found a problem.
Opening the machine I found a LOT of dust, but nothing else of note.
I re-seated the daughterboard and blew out as much dust as I could, and tried
again, without the 256K front panel plug in module - still errors. Bizarre
failures of commands from the CLI. PageStream worked flawlessly, though. :-)
There are several more experiments I want to try - using kickstart
1.1 and the Michigan Software memory test, removing the Insider board, etc.,
but I think the problem is probably in either the bottom 256K of CHIP ram or
in the WCS rams. If it is in CHIP ram it must be at a very low address, where
the memory tests (which only test what is not already allocated by the system)
can't find it. The computer has worked the last two times that I used it,
but I was not doing anything very exotic, so maybe I missed the bad bits.
I have done two mods to the system. I grounded the PALs on the
daughterboard (like in the AC article, only correctly) and installed a chip
to make the audio output low-pass filter switchable. These were both done
well over a year ago, with no problems.
Questions:
* Is there a kickstart ram test that can be run to test the WCS? I
guess that it would have to be on a kickstart type disk, load itself into
chip ram and then start itself up. A pointer to such a beast would be appre-
ciated. If it's short, and you have it, maybe you could email it to me.
* Does the guru right after kickstart prove the error is in the WCS, or
does something execute out of regular system ram while waiting for the
boot disk?
And, (probably) unrelated
* Since I first got the computer it has had a slight problem with sound.
Every once in a while, the sound output will glitch. This happens more in
games and applications that pump a lot of digitized sound out through DMA.
Usually it's a short burst of random noise, but with games that just replay a
constant sound over and over (the engine noise in flight simulators, for
example) the sound buffer seems to get corrupted, and it gets worse and worse.
In F18 Interceptor it eventually sounds like the engines are ready to just
rip themselves apart. Reloading the game restores the sound track. Is this
a bad custom chip (and how much is it to replace) or indicative of a general
memory problem? Nothing else seems to have problems with DMA.
Any help would be appreciated. If I can't isolate the problem with
a test beyond knowing it's one of 16 memory chips, I might just replace them
all, and add sockets. A tech from work here will do the work for me (at home,
of course), for a very low price. I can probably get that done for about
$100 or so, not including the sockets. It would probably take more than that
to get a local repair place to LOOK at the computer.
Any help, tips, or pointers will be appreciated!
TIA (thanks in advance), Steven Meloche
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