PERQ T2 faults
ard at p850ug1.demon.co.uk
Mon Aug 20 16:37:49 CDT 2007
> Tony Duell wrote:
> > What I would do is first check that the hard disk is going ready -- that
> > is with a logic probe on the control connector with the drive cabled up
> > to the PERQ.
> Presumably I can do that on the bench - I think it's just a case of applying
You can, yes. Althought personally, I'd do it in the PERQ (a 50 way cabel
with an edge connector on one end and a 2-row header socket on the other
is very useful for cabling the DIB to the EIO in this sort of situation
;-)). Reason being that if the PERQ isn't asserting drive select or
something, you'll spot that oo.
> power and twiddling the appropriate drive select line so that the drive
> enables the output control signals... (I'll check via bitsavers - I think the
> drive selects are active-low)
YEs, just about all the signals on the ST412 control connector (and for
that matter a floppy drive connector) are active low. The drive outputs
may well be (should be!) open-collector signals, requring an external
A couple more things. The 3 wire power connector on the DIB is +5V,
Ground, -5V. Not +12V anywhere. And the DIB breaks the rules by using
totem-pole drivers to drive the disk signals. if the power cable falls
off, these darn things can assert the appropraite signals and corrupt the
disk. Don't ask how I found that out!
> Worst-case if the drive's hosed, we've got various install disks - just a
> question of whether there's a formatter (low or high level) in there somewhere!
The formatter wasn't included with any normal PERQ OS distribution. But
you should have the engieer's disk somewhere that includes it.
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