20 Sep
2001
20 Sep
'01
4:53 a.m.
"Bill Sudbrink" <bills(a)adrenaline.com> said:
I brought this up some time ago, but never
got a satisfactory answer...
When I use the above combination (regardless
of CPU board), while the system in general
works fine, the deposit/examine functionality
of the front panel stops working. Somebody
said they knew of a fix, but then never posted
anything else. I've looked at the schematics
(I have them for both items) and can't for the
life of me see anything that would conflict.
Any help greatly appreciated.
Here is some of the IMSAI front panel gottas:
MWRITE pin 68 - This signal needs to be generated
by one source and one source only. It is generated
by the IMSAI front panel (by a deposit) so make
sure this signal is disabled on the CPU board when
used with the IMSAI front panel.
PROT & UNPROT pins 20 & 70 - The IEEE 696 standard
says that these pins will be at ground. Some
motherboards ground these lines. But grounding
these pins on the IMSAI front panel will disable
the front panel. To fix this, cut the traces,
on the front panel, right at edge connector
pin 20 and 70.
Data Out Bus - When the IMSAI front panel does
a deposit operation, it expects the the data
on the Data In Bus to be reflected on the
Data Out Bus. Some later CPU boards disabled
the Data Out Bus to cut down on bus noise
especially above 2MHz.
Regards,
--Doug
=========================================
Doug Coward
@ home in Poulsbo, WA
Analog Computer Online Museum and History Center
http://www.best.com/~dcoward/analog
=========================================