17 May
2005
17 May
'05
4:16 p.m.
Upon the date 19:29 16-05-05, Tony Duell said something like:
I know little about the 9845 hardware at present. I wish I had my own 9845
but haven't found an intact one yet.
I also know little about it, even though I've been doing battle with one....
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
YEs, but _which_ 9845 processor?
Based on that description I would bet that whomever stated the 250 CPU was
the same, except for ucode, had intended the comparison to be to the LPU
which is implied above to be equivalent to the "main" processor (vs the I/O
processor which has less responsibility for calculations, logic processing,
program control, etc.).
AFAIKL the 2 processors in the 9845 are actually very similar, even though
the PPU has the I/O bus hung off it, and the LPU doesn't. If anyone has a
9845 _without the high speed LPU option_, it might be worth pulling the
LPU board (the far right board in the right hand cardcage) and looking at
any numbers on the bottom of the processor bybrid. IIRC the PPU is a
5061-3001 in my machine.
Being a hardware guy, I was wondering if the HP250 used a custom HP
module, or if it was a few boards of TTL and bitslice. If the latter, it
would be itneresting to see how the schematics compare with those for the
9845 high-speed LPU.
The LPU cotnrol board in my 9845 could take 4K PROMs in place of the 2K
ones (that's what the soldered jumper link is for), BTW, So it would be
possible to use these boards to make a processor with 4K of microcode.
[...]
I feel this may give you something to work with as you
reverse engineer
the FWIW, a reverse-engineered 9825/9831 schematic is
on the HPCC schematics
CD-ROM (along with similar diagrams for the 9100B, 9810, 9830, 9815, some
late rmachines, and most of the handhelds)
Hmm, great (re: 9825 schema)! I will track down that CDROM again and buy
it. I have a link stored somewhere.