16 May
2005
16 May
'05
11 a.m.
Upon the date 16:45 15-05-05, Tony Duell said something like:
Tony, the HP250 CPU is said to be the same as the 9845* except for
different microcode. Reference this website if you can:
http://www.hp-eloquence.com/history/history.html
Anyway, a couple of lines of text in the description on that site states:
"Technically a descant [sic, probably meant descendant] of the HP9845
workstation it was targeted at the commercial market." and further went on
to state: "The HP250 used a HP proprietary 16 bit processor (similar to the
one used with the HP9845) supporting 192 Kb to 512 Kb of memory."
Now, to give some real meaning to this posting for you, refer to the set of
schematics for the HP250 on bitsavers:
http://www.classiccmp.org/bitsavers/pdf/hp/250/45251-90001_HP250sch_Jun82.p…
Problem is that this is a 14.5 meg file and I think you are still on a slow
connection. Maybe somebody near you reading this could print it out for you
or somehow get you the file on a CD-RW or something if you use Adobe
Reader. Anyway, pages 74 and 75 show the board layout and schema,
respectively. Whole document is 142 pgs.
I feel this may give you something to work with as you reverse engineer the
9845. You didn't say, and I assume it to be very much the case given the
lack of tech manuals for our own 9825 machines, that there was any tech
manual (w/schemas) for the '45, hence my suggestion of this file to at
least get something to help you along.
I've got an HP250/30 and I dang near passed out when I discovered this
drawing set on bitsavers last year! About 15 years ago I even drew out the
schematic of the CPU board and part of the HP-IB board just to learn
something of the machine. I had been resigned to *never* find anything such
as this during the past 20+ years I had the machine. Never say never, as
they say . . .
Thanks VERY much to whomever scanned and uploaded that seemingly rare HP
document!
Regards, Chris F.
NNNN
Left there
and went to see the guy that I'd meet that morning. He gave
me a ***MINT*** Visual 50 terminal, a MINT Sage II computer with ALL the
I haev a Sage II (the later model with half-height 80 cylinder drives),
and the _excellent_ owner's manual with full schematics in the back. What
I don't have is an OS for it :-(. If anyone has the set of original disks
that came with such a machine, I am looking for copies (IIRC it was the
UCSD p-system, with some Sage-specific utilities).
docs, a working HP 9845B, a stack of manuals for
the 9845, a couple of HP
There's a 9845 in many bits on my bench at the moment. %deity it's a
complicated machine.... I think I just about understand the buses now
(and evne that's complicated -- there are 2 main buses, essentially
'language' ROMs and memory on one, 'peripheral' ROMs and memory on the
other (one ROM drawer is on each bus), both processors have access to both buses, the video system can access both buses via
the peripheral
processor's buffers, etc. Evne the PSU is about twice as complex as you'd
expect!
-tony
Christian Fandt, Electronic/Electrical Historian
Jamestown, NY USA cfandt at netsync.net
Member of Antique Wireless Association
URL: http://www.antiquewireless.org/