Some more 14MHz '816 problems

[jmaes@sonycsce.com (Jan A. J. Maes)]

I too had problems when updating my ZipGS 8/16 to 14MHz.  I couldn't get
it to work and I finally gave up.
After reading arekusu's comments yesterday I decided to do some more
experimenting.

My configuration is :
ROM 03 IIGS with latest ROMs
Slot 1     ProGrappler
Slot 2     empty
Slot 3     ZipGS 8/16
Slot 4     SoundMeister
Slot 5     empty
Slot 6     sometimes PC Transporter
Slot 7     High Speed SCSI with 300MB HD & 650MB MO
Memory = 5MB

By the way, I would like to thank the person who suggested I'd change my
High Speed SCSI to slot 7.  I forgot your name, but it bumped my transfer
rate from 400k to 800k+ on my HD.  It didn't solve the problem though.

I originally had a 10MHz 65816 CPU although it was a 8/16 ZipGS with a
full size 32MHz oscillator.  R1, C13 & C14 are missing.  Installed was
16kB of 70ns chips.

I purchased the following (just to be safe) : 3 pcs of 14MHz 65816, 2 pcs
of 40MHz osc, 2 pcs of 55MHz, 1 pce of 60MHz and 25ns SRAMs.  I also
replaced the 74F00 with a 74HC00.  The 74F02 I did not replace.  All as
indicated in the FAQ (Rev. 95/2).

These are the results :
RAM : no problem whatsoever.
Speed :
      32MHz - rock solid (with any CPU and 74F00/74HC00)
      48MHz - no boot (OA-SA-Ctrl-Reset doesn't work)
     55MHz - no boot (OA-SA-Ctrl-Reset doesn't work)
     60MHz - will boot, but will randomly crash (with any 14MHz CPU and
74F00/74HC00).

At 60MHz, crash is sometimes after 1s, sometimes halfway thru booting
GS/OS.  After crashing, the control panel can be accessed normally.  If it
does get far enough in booting GS/OS, it will report problems finding the
HD and FST's.  Booting into ProDOS 8 however, is generally no problem. 
Could it be a termination problem on the SCSI chain?  Or a DMA problem? 
Are my SRAMs fast enough?

I noticed that T1 was open, while T2 & T3 were closed.  On my friend's
10/64 ZipGS all three were open.  So I thought that the T's are used to
encode the clock speed at which the ZipGS is running.  When I opened T2 &
T3, when booting at 32MHz, the clock was still reported as 8MHz, so
apparantly they do not set clock speed as I thought.  The difference at
60MHz is that text now is garbled and the control panel no longer works. 
I can also no longer boot into ProDOS 8.
Does anybody know the function of T1, T2 & T3 plus T4,T5 & T6 and for that
matter of all connectors?


PS : Doede, it was me that you are looking for.

-- 
Woe to you oh Earth and sea for the Devil has sent the Beast with wrath.  Let him who hath understanding reckon the number of the Beast for it is a human number and its number is six hundred and sixty six.
Iron Maiden -- the Number of the Beast