20 Aug
2007
20 Aug
'07
2:37 p.m.
Tony Duell wrote:
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.
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 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
pull-up resisotr.
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.
-tony