At 09:54 AM 97/01/28 -0800, you wrote:
....snip....

>I've always been told me that putting printers and disk drives on the
>same HP-IB channel is a no-no, because slow devices shouldn't be mixed
>with fast devices on the same channel.
>
>Could this have contributed to the problem?

It used to be (back in the "Classic" days) that there were two kinds of HPIB
devices, - called slow and fast  - which referred to their respective HPIB
device loads. Various systems could only support a specific number of
"high-speed" GICs. GICs were not really high-speed or low-speed per se -
rather they were considered to high-speed if at least one device connected
to it was "high-speed".

Eventually HP did away with all "low-speed" devices and all the newer
devices were considered as "high-speed" - including all the relatively new
HPIB printers.

The adage about not mixing low-speed devices with high-speed devices really
only applied to some very specific devices - the HP7970 tape drive, which
required it to be the only device on a GIC - as well as the HP2608A printer,
which also has its specific channel sharing characteristics and requirements
- if my fading memory serves me correctly.

In the current PA-RISC environment, you couldn't really mix high-speed and
low-speed HPIB devices because - as far as I know - ther are no low-speed
HPIB devices that work on a PA-RISC machine.

However, there is a very good reason for not mixing HPIB disc drives with
HPIB printers or tape drives - if at all possible. That reason is to prevent
the exact problem that Mr. Largent experienced - ie. the inadvertant
resetting of a HPIB printer device channel number that matches an existing
channel number of a disk drive.

I would venture to speculate in hind-sight, that if the possibility of
duplicate device addresses on the same HPIB channel had been considered in
the aforementioned problem situation, a reload/install could have been
avoided. Of course, hindisight is always 20/20. And, besides, it is not
always possible to afford the luxury of multiple HPIB interface cards due to
other constraints (such as money, available full-height slots, etc.).

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