18 Dec
2009
18 Dec
'09
2:34 p.m.
Tony Duell ????????:
It would be an experiment, mostly. It would probably be easier to edit
or tweak a disc on a PC, as well. But I would like to have more
options for my 20Mb and 40Mb discs.
>> I wonder why HP went away from the 9914 in the
drive units (all later=20
>> drives seem to use either the 8291 or the Medusa) while keeping it in=20
>> the host computers.=20
Perhaps the 8291 used less code on the microcontrollers? Or perhaps it
could do seomthing on it's own, unlike the 9914, such as assert NRDF
when it's databuffer was full? Come to think of it, wasn't the 8291
almost "smart", like a hard coded microcontroller?
I still think it would be a useful project for
somebody to make a
HP-drive-emulator. Mot using a PC, but using a microntroller, HPIB
buffers, the minimal (if any) logic you need to handle HPIB, and a CF
card. Make it 'open( and I'll build several...
Or even a SATA, PATA, USB storage interface. Such a stand alone
emulator would be very useful.
There's a fair description of the Amigo protocol floating around as
well as the CS80 spec as a PDF on Bitsavers. Since all the HP drive
controllers are built around Intel microcontrollers, shouldn't be too
hard to use a modern very high speed 8048/52 compatible. One advantage
would be the potential ability for one unit to accept more than one
address. Xebec published some source and/or pseudocode for their
controller board micros, which might help make things easier.
I have never actually seen this Xebec controller in an
HP drive unit, but
I'll believe it exists.
I've actually seen just one inside an older HP unit at Halted's. A
very poor photo of this board is in the hard disc tech/service manual,
on page 1-8 of the service manual and page 32 of the Bitsavers PDF ...
(as 9133_9134_9135_9121_9122_ServiceDocumentation_509pages_1985.pdf),
as Fig. 1-3, along with a very brief description. If I can find my
pictures I'll put them up somewhere.
I have two Xebec controllers, one of which, IIRC, is attached to one
Seagate 5Mb and one Shugart 5Mb, and the other controller attached to
one Shugart 10Mb. One or two more controllers are not being used at
the moment. I have several different ROMs for them. It took some
experimentation to get them working right without docs or any clues
from anyone. I also have one 9133XV with a bad floppy
controller.
I can;t see why that would be a problem. The HP
protocols are all block,
not file, baeed (unlike the Commodore drives for the PET). The drive
doesn't have any idea what OS is talking to the it, it has no
understanding for the directory or the filesystem.
OK, then I was given the wrong info about them. Seems a waste of
processing power to use block transfers instead of letting the drive
handle all that. Drive capacity also need not be limited by the host's
design.
(I'd like
to find out how to format discs on a PC for use in the 9134
drives. I could probably use bigger discs if they could be formatted
properly.)
I wouldn't bet on it. I am pretty sure the later drives, at least (9144H,
etc) check that the hard drive actually matches what is expected (I have
been told the cotnroller tries to select non-exixstant heads and makes
sure the drive asserts the erorr line, things like that).
The 9133V controller (I assume there's a 9134 version, if only becuase
you could trivially remoove the floppy drive and controller from a
9133V) can be jumpered to work in 3 ways :
There is/was indeed a 9134V & XV. The other difference from the 9133
was that the front was "blank", as in no opening for the floppy. I may
still have the HP catalogs with those, as well.
--
jd
"Calling J-Man Kink. Calling J-Man Kink. Hash missile sighted,
target Los Angeles. Disregard personal feelings about city and
intercept."