31 Jan
2007
31 Jan
'07
10:10 p.m.
Richard wrote...
All the HP 21MX posts got me interested in finding out
what I have with
the
HP 2112A I recently got and what I'm missing.
Woohoo, a M series. Those
aren't so common.
The back end (where all the I/O cards go) is empty.
You'll want some I/O cards. Also get a TBG (time base generator), many OS's
want this.
In the front there is the DCPC, Memory Protection,
M.E.M. (Memory Extension Module), 3 memory cards and Memory Controller.
Sounds like
you're all set there. Make sure you have the DMS daughterboard
in addition to the base set microcode daughterboard. I *THINK* I have a
spare DMS microcode board for the M series.
I
believe I can see 3 loader ROM chips installed on the CPU board (assuming
I'm looking in the right place - front right side of the board as I'm
facing
it).
Do a IBL of each loader rom and jot down the first 8 words or so of the last
64 words of ram. Then you can look in the loader manual and see what loaders
you have. Some versions of the M series metalwork allow you to see the rom
part numbers directly though, that may be more expedient. Don't bother with
the options written in the front door panel, they are often outdated/wrong.
On some boards loader rom 0 is soldered in and is paper tape. However, I
have a few M series boards where ALL the roms are socketed, and I have found
other loader roms besides paper tape in rom 0, so check all 4, not just the
3.
Of the 3 optional Control Store modules in the back,
the middle one is
mounted under the CPU, but the other two are not there.
I do not recall for sure if
the base set microcode MUST be the bottom right
(as viewed from the top front). I think it may actually be able to reside in
any of the three positions, but I could be way wrong about this. The base
set is of course required. Then you'd want the DMS (optionally) microcode
too if you want to use memory above 32kw (and have that much memory). Note
that if you want DMS, you have to set jumpers on boards in addition to
installing the microcode. Ditto if the DMS option was removed.
The back label says "2112A" and lists the
following options:
12978A (Writeable Control Store Diagnostic)
12992B (Disk boot ROM)
12992C (Terminal boot ROM)
I figured out from the bitsavers document and another online document that
these are the 3 ROM options I saw. The paper tape loader ROM is soldered
in
with the M-series machines, according to the online documents I read.
Not on all M
series machines it's not. I have never seen or heard anything
about 12978A Writable Control Store Diagnostic. I'm very intruiged.
12897A (DCPC)
12892A (Mem Protect)
13187Ax2 (16k Mem)
I'm assuming theres MEM (memory expansion module) and a
memory controller
(2102) in there somewhere too?
So it looks to me like I need some I/O boards (13175
disk drive interface,
12966 or 12968 terminal interface, 12597 paper tape interface), and
probably
the other Control Store modules to flesh this thing out (not to mention
the
cables to connect to peripherals). Does all that sound right?
You want some I/O
cards, the problem is which ones. Do you have any
peripherals for it already? I use mostly 12531's, and some 12966's for
consoles. Paper tape can be one of several boards. There's several different
disk drive interfaces too, depending on what drives you have or want to get.
You may or may not need other control store modules, depending on if the
base set must be on the bottom right (ie. is what you have the base set or
some option set).
Sounds like you have a handle on it to me.
Jay