HP 1000

Bob Shannon 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
I/O timing.

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

> 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

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