Re: TWGS questions

[spec@vax2.concordia.ca (Mitchell Spector)]

In article supertimer@aol.com (Supertimer) writes...

>spec@vax2.concordia.ca (Mitchell Spector) wrote:
>
>>    You mean 8K (as in 8192 Kilobytes) of cache. :-) There is
>>actually 16K of static RAM present, but half of it is used for
>>TAG RAM.

    Oops, I meant 8192 bytes of course. I only noticed that typo
after my original post went out and it was too late to cancel it.

>>    Examine the ribbon cable that plugs into the 40-pin CPU socket
>>on the IIgs motherboard. There should be a black dot somewhere on
>>it--if not, you have one of the original (flakely) cables Applied
>>Engineering made a policy of replacing.
>>
>>    The old cables made the card very, very unstable. I confirmed
>>that was true with my 6 MHz TransWarp GS, and one of the reasons
>>it has been boxed up and put into storage for the past 4-5 years
>>now. AE may no longer be around, but you can purchase a home-made
>>replacement cable with gold tipped pins for around US$14 (I can't
>>remember who offered this service, maybe Bill Shuff? A Dejanews
>>search should help track him down).
>
>I disagree because failing in 16-bits first is a sign of a failing
>65C816 of the old design.  Those chips exhibit this symptom
>when pushing beyond 7Mhz or so.  However, as a chip ages,
>the failure threshold may drop below the original 6Mhz.

    Well in my experience, if you have an unstable ZipGS or TWGS,
lock-ups and crashes occur much more often under GS/OS than any
ProDOS 8 applications. For example, when I was having trouble
with 64K of cache (versus only 32K enabled) ProTERM 3.1 seemed
to run relatively smoothly but the IIgs Finder would easily
lock-up, usually within seconds of using it. I assume there are
many more caching operations taking place when running native
software.

    Incidentally, my ZipGS has been acting more and more unstable
these last couple of months (even switched down to 32K of cache).
A moment ago I decided to do something about it and it seems to
have worked--I'm even running stable with 64K of cache! What I did
is place Pentium heat sinks over *every single chip* on the ZipGS
(the ASIC, 65C816 and SRAMs). There are three heat sinks in total.
In the past opening the lid and pointing a desk fan at the card
kept it running stable, so obviously it was a heat related problem.
If this proves successful (I'll know in a few days) I think I may
try doing this with my TransWarp GS. :) Originally I had a heat
sink only over the ASIC, which helped considerably, but not in
making things 100% stable.

>If it were the cable, then 16 and 8 bit software will fail at the
>same time.

    Not neccesarily, as I stated above, it seems only logical that
16-bit software is more prone to crashes and lock-ups than 8-bit
software. In any case, a cable without the black dot is asking for
trouble and I would recommend changing that before purchasing a
new 65C816.

Mitchell Spector
spec@vax2.concordia.ca