24 Sep
2004
24 Sep
'04
7:10 p.m.
1) Commodore SFD-1001
This is the IEEE-488 (PET) single-drive that looks
very much like a VIC/C64 1541 serial drive.
The drive powers on, and both the POWER and drive LED
come on solid RED and stay that way - no other activity
is observed - it doesn't matter if the IEEE bus is
connected or not, and resetting the IEEE bus (via PET
power-on) has no effect. If the PET tries to access the
IEEE bus, it hangs, presumably waiting for an acknowlege
that never comes (?)
It looks like the on-board CPU is not running at all.
I would guess that's likely to be the case (although I've never worked on
this unit).
In which case I'd start by checking the +5V power rail, then check the
CPU clock and reset pins (make sure the thing isn't held in the reset
state), then see what the aaddres and data lines are doing.
-tony