29 Jun
1999
29 Jun
'99
4:14 a.m.
On Tue, 29 Jun 1999, Bill Sudbrink wrote:
So far, all of the power in my IMSAI checks out OK.
I've brought it up with the MPU-A installed and I
get flashing lights. Press the STOP switch and I
get solid lights. Now the weird part: When I
toggle the address switches and press EXAMINE,
here's what I get on the address lights:
Legend: O - light off
X - light on
- - switch off
^ - switch on
Lights OOOO OOOO OOOO OOOO
Switches ---- ---- ---- ----
Lights OOOO OOOO XOOO OOOO
Switches ---- ---- ---- ---^
etc...etc...etc...
So I think the lights are working. I think something
is wired strange in the panel? Are there Z80 mods I
should look for?
This frequently indicates that the cable connecting the CPU card to the
front panel is connected or wired improperly. This cable is used to jam
data from the front panel into the CPU and will cause real interesting
things to happen if incorrect or disconnected.
One thing to check also... Various manufacturers tended to wire the
CPU connectors differently, and on occasion you would find that the cable
had been rewired to deal with a third party CPU card...
The 'normal' IMSAI cable is just a ribbon cable with DIP headers crimped
on each end. If it looks different than that, it has probably been
modified.
-jim
---
jimw(a)computergarage.org
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