[Coco] My beloved coco seems to have had a stroke

[Gene Heskett]

On Monday 24 September 2012 11:13:45 Robert Gault did opine:

> Gene Heskett wrote:
> > Tonight, on powering it up (it has hdbdos) it shows the HDB-DOS1.0A in
> > the middle of the screen, and essentially stops.  It usually waits
> > for the hard drives to spin up and do their initial calibration
> > sweep, and assert the drive ready signal, at which point that 15
> > second countdown of marching dots that gives one time to hit the key
> > indicating what to boot from, or take the default hard drive boot.
> > 
> > I can hear at least one drive do that head scan, but the upper drive
> > HD 1 never turns off its little led unless I remove its drive cable. 
> > HD 0 does flash it once at powerup, for maybe 1/4 second.  And the
> > countdown dots never start.  Ever.
> > 
> > Hitting the reset button at that point, then typing DOS0 gets an
> > instant I/O error, which may be that I need to do a drive off or
> > drive on first, I've forgotten which enables the first 4 floppy
> > drives.  Power supply voltages to the multipak, and to the drives are
> > good, the 5 volts is about 5.08, the +12 for the drive motors is
> > about 11.98.
> > 
> > Next step suggestions please.
> > 
> > Cheers, Gene
> 
> Gene,
> 
> What happens if you disconnect HD0 from the system? Do you then have
> access to the other drive?
> 
IIRC the bottom drive is drive 0.  Disconnecting either/both has no effect.
I'll have to dis-mount the drive to be able to read the jumper table on top 
of it to verify the assignments for sure.

Unplugging the TC^3 gets a hard drive not available message.

> I've a very old SCSI Tandon TM 252 drive as one of two in my system. At
> random, it gets stuck on the landing pad and I have to move the heads
> manually to get it active. Same symptoms as yours, drive light always
> on but no I/O.

This is stiction then?  When both are plugged into the cable, its the upper 
drive whose access led (its on the bottom of the pcb) stays on.  I can only 
hear one calibration sweep.  The drives are identical Seagate 1Gb Hawks, 
but I wouldn't think the spin up times would be that well synchronized.

I would assume too, that unplugging what I think is drive 1, should allow 
drive 0 to proceed.  But it does not.

I'll have to do major house cleaning to make room to dis-mount them and 
power them up laying where I can bump them on a corner to assure starting, 
and will see about that today after loading about 40 rounds to fire form a 
30-06 into a 30-06 Ackley Improved.  Its getting on toward deer season & 
I'm rusty.  The right end of the desk has at least a foot of paper piled 
up, and likely several boxes of shells since my reloading bench is only 2 
feet away.

Thats the toys will expand to fit all available space theory at work.  I'm 
sure you are familiar with that, its a corollary of Murphy's Law :)

Thanks Robert.

Cheers, Gene
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