bshannon at tiac.net
Sun Dec 18 09:20:30 CST 2005
I don't have schematics for the 12555 board, but I am very familiar with
The 12555 is not strictly compatible with M/E/F series CPU's due to their
The 12555 generates its Z axis signal based (indirectly) on the I/O
In a faster machine (E and F series) a new set of X/Y values can be loaded
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
a capacitor value. Longer RC values were commonly used with storage tube
If your running this board on the 2100, timing is not the issue, but the RC
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
> 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)
> - 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.
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