Re: Drive Keeps Running...

[dempson@actrix.gen.nz (David Empson)]

Tony Cianfaglione <ab616@chebucto.ns.ca> wrote:

>    The disk drive just won't stop running.  I have to use a Control-Reset
> to stop it at each interval when I want to remove a disk.  It will allow
> me to enter any commands I want at any time but the drive keeps on running
> (much like the Energizer Bunny).

So it stops running while you hold down Control-Reset, but then starts
running again as soon as you let go?

If so, it sounds like the one second timeout circuitry inside the IWM
chip is faulty, preventing it from timing out.

On the other hand, if Control-Reset is stopping the drive until the next
time you access it, then there is probably a different fault inside the
same chip.

>    Plugging an external drive in the back causes the external drive to
> keep running while the built-in drive stops so it is obviously passing the
> problem along out the Smartport to the external drive.  Everything else
> runs and works fine.

This description doesn't sound quite right.  The internal and external
drive select signals are independently generated by the IWM chip.  They
cannot both be active at once (unless there is yet another hardware
fault), and simply plugging in an external drive would not cause the
drive select line to switch over.

It is possible that both of the drives are enabled, but the power supply
cannot provide enough power to run them both at once, and one of them is
"winning".  This doesn't seem very likely, however.

Is this a better description of what is happening?  I suspect the
permanently enabled drive is changing according to which drive is
accessed, i.e. if you do a CATALOG,D2, then the external drive spins
forever, then if you do a CATALOG,D1, the internal drive spins forever,
toggling back and forth according to subsequent commands.


Whatever the exact details, it sounds like there is an internal fault in
the IWM chip, so you would have to replace it.

>    It is a 255 ROM [using print peek (64447)] but it also has the color
> box (OA + CA) diagnostic screen that runs forever and never says anything
> like System OK.

The original IIc firwmare (which you have) doesn't have a proper
self-test, just this silly colour pattern display.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand