18 Dec
2005
18 Dec
'05
7:20 a.m.
I don't have schematics for the 12555 board, but I am very familiar with
them.
The 12555 is not strictly compatible with M/E/F series CPU's due to their
I/O timing.
The 12555 generates its Z axis signal based (indirectly) on the I/O
backplane
timing.
In a faster machine (E and F series) a new set of X/Y values can be loaded
into
the registers before the Z axis signal is done. This will produce a glitch.
If your using this board in an E or F series processor, I'd recommend one of
two approaches to work around this issue.
1. use programmed I/O rather than DCPC (DMA) transfers.
2. Double up each point sent, sending the same X/Y values at least twice.
Also note that there is an RC timer on these boards that can be set by
changing
a capacitor value. Longer RC values were commonly used with storage tube
displays.
If your running this board on the 2100, timing is not the issue, but the RC
timer
settings may be.
----- Original Message -----
From: "Christian Corti" <cc at corti-net.de>
To: <cctalk at classiccmp.org>
Sent: Sunday, December 18, 2005 6:19 AM
Subject: HP 1000
Hi,
our museum recently got "some" (a dozen) HP 1000 with "some" spare
parts
and "some" tapes. Currently we're building up some of the stuff to get a
running system. For now, I've put a 2100S, a 2117 (1000F), I/O extender,
two 7970B tape drives (one with the 200/556/800 bpi option), one 2748A
tape reader, one HP 8100 tape punch (basically a Facit 4070), a HP130C (?)
rackmount oscilloscope, and a 7905 disk drive with its 13037C controller
into the three racks we have.
Included are the original distribution tapes of RTE-II, RTE-III, RTE-IIIM,
RTE-4, RTE-4b and RTE-6/VM, DS/1000, Signal/1000, Fortran, etc., a huge
pile of paper tapes (original HP), and nearly all paper documents
(manuals, schematics). But some parts are missing, so here are my (first)
questions:
- Does someone have the schematics of the 12555 dual D/A converter card?
They are not on bitsavers yet. We've attached the D/A card to the scope
and ported the PDP-8 kaleidoscope program to the HP2100. There are a lot
of glitches in the analog signals and we want to find out where they
come from (it's not a software bug, all test programs on all D/A cards
we have show the same symptoms).
- My only diagnostic tape (24396-13501 rev. 1926) has read errors in file
7 and in the last files. There is (was) a file in the SIMH package
called hp2100_diag.txt that insinuates that there must be a TAP image of
the 24396-13601 rev. 2040 diagnostics tape. Is there a chance to find it
somewhere? I really need a working diagnostics tape.
Christian