30 Dec
2008
30 Dec
'08
11:35 p.m.
Tony Duell wrote:
The HP drives work at a much lower level. The file system is managed by
the host computer. The commands to the disk drive unit read/write bocks
(essentially the same thign as sectors). It's up to the host to turn
those into a file system.
This is not as problematic as it may seem. The uIEC can auto-update the
firmware, so I could simply write a special version of the SW for
HPIG/GPIB (even different flavors for the various command sets) and the
owner can simply place the flavor desired onto a flash drive, turn on
the unit, and it will program itself with the correct DOS.
You could probaly find an HP150 or an HP9000/200
machine fairly easily
on E-bay.
I am hopeful someone finds enough value in the possibility to provide a
unit for testing. Still, this is very premature, since I still need to
get the PET IEEE stuff working.
Now I don;'t know the exact details, but I read (I
think on one of the
HP9845 pages) that somebody had written an HP drive simulator programs
for PCs fitted with an HPIB card (I believe said program has source
available if you want to look for hints on the command set, etc). But one
thing that this weg page siad was that it couldn't run with a 9914-based
HPIB card, since HP did something that was essentially against the
standard and which the 9914 couldn';t do. I do know that HP used the 9914
in their computers quite a bit, but that the drives used the Intel 8291.
Of course if you're planning on bit-banging the HPIB protocol on the pins
of a microcontroller (I think you need a little external logic, there is
one transition where you can't take arbitrarily long to change one of the
signals), then this won;'t be a problem.
It'll be a bit-bang approach, so save HW costs, but I can wire up some
TTL logic if needed.
Jim