Re: IIC SELF-TEST: Does it test the IWM drive-controller?

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

stephen e buggie <buggie@enzu.unm.edu> wrote:

> I bought several IIC's at a school auction.  One of them passes the 
> internal self-test with SYSTEM OK, but the drives spin and swap but dont
> load.
> 
> Does anyone know whether the SELF-TEST actually tests the Integrated Woz
> Machine (IWM) chip that controls the disk drives????

It probably senses that the IWM is present, but won't be able to test
whether it is working properly.

There is a limit to how much the self-test can do.  Since there is no
special hardware to assist with the testing, it can only check things
which can be readily identified by the CPU.

For example, it can't automatically tell you that the video isn't
working, because there is no way for the CPU to monitor the video
output.  It can't tell if some of the power supply voltages are missing,
because most of the computer will work fine without +12V and -12V.

In the case of the IWM, the self-test can't do very much without
performing actual disk I/O, because most of the parts of the IWM which
can be written to by the CPU cannot be read back.

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