Re: Drive Keeps Running...

[Tony Cianfaglione <ab616@chebucto.ns.ca>]

Hi David,

On Sat, 19 Jun 1999, David Empson wrote:

> 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.

   This is what is happening - it stops until the next command.

> >    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.

   If I start the IIc _without_ the external drive, the internal drive
will run on and on.  Starting the IIc _with_ the external drive plugged in
causes the internal drive to run momentarily and then stop with the
external drive then starting up and running on and on.

   With a boot disk in the internal drive and the external drive plugged
in, ProDOS will boot and the cursor will appear on the screen.  The
internal drive will stop and the external drive will run as the system
polls it.  However, the external drive will keep running even after ProDOS
has loaded and the cursor is on the screen.  I don't have to type in
anything and the external drive will run on and on.  The same occurs with
DOS 3.3.  A Control-Reset will stop it but probably breaks any program
that has loaded into memory at the same time.  What does a Control-Reset
do to a program?

> 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.

   Both drives do _not_ run at the time,; the polling jumps between them
but the last one in line will run on and on.

> 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.

   I don't have to enter any commands and the esternal drive run on and
on.  If I enter CAT,D1 while the external drive is running, it will stop
and the internal drive will catalog the disk.  Once the data is on the
screen, the internal drive wil stop and the external drive will once again
start up and run on and on.

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