HP & 800BPI / was Re: Tape cleaner on eBay

Brent Hilpert hilpert at cs.ubc.ca
Fri Oct 9 14:49:12 CDT 2015

On 2015-Oct-09, at 10:28 AM, Marc Verdiell wrote:
> Glen,
> I'm right in the middle of resuscitating an HP7970E (1600 bpi with the HP-IB
> interface). The main problem I had so far was the rubber in the reel hubs
> had completely fused to the tape reels that were left on the hubs. I had to
> disassemble the hub locking mechanism and use lots of careful X-Acto knife
> work to separate the two. A few tape rollers were rough or stuck - just
> oiled them for now. Then it started to work, I am very surprised. There are
> three red switches on the motor control board inside to make the tape go
> forward, reverse and fast rewind. So it's pretty easy to test if the
> transport works and the motor servos and tension arms move how they are
> supposed to.

I had that problem with the stuck reel hubs. Failed to take my own advice-to-self to leave the reels unmounted and they stuck again, although easier to get off this time as it hadn't been many years under pressure.

> Brent, 
> Wow, looked at your site, and you actually wrote a HP 2100 cross-assembler?
> Nice. Would it work for the HP21MX too? Did you compile it using the command
> line tools in XCode?

I had originally written it in a re-targetable cross-assembler in a now-outdated development environment under MacOS9. Last year rewrote someone else's assembler (C source) - it should work in any standard C environment. Was using it to re-assemble HPBASIC.

I'm not familiar enough with the 21MX machines to say what may have been added/changed from the early 2100's in assembly terms, but it shouldn't be difficult to add to the assembler. Can send you the source if you wish.

I had a simulator written in the old OS9 environment too, but haven't brought that into a current state.

> Marc
> ==========================================================
> Date: Wed, 7 Oct 2015 13:29:37 -0700
> From: Brent Hilpert <hilpert at cs.ubc.ca>
> To: "General Discussion: On-Topic and Off-Topic Posts"
> 	<cctalk at classiccmp.org>
> Subject: HP & 800BPI / was Re: Tape cleaner on eBay
> Message-ID: <858603D2-2D79-45D6-993C-A8939D996815 at cs.ubc.ca>
> Content-Type: text/plain; charset=us-ascii
> On 2015-Oct-07, at 12:56 PM, Glen Slick wrote:
>> I have an 800BPI 7970B in a 2113B rack system. I've never gotten 
>> around to trying to get it up and running. Are they fairly reliable 
>> drives to get going again? I don't have any other 800BPI drives to 
>> write any tapes to read with it.
>> On Wed, Oct 7, 2015 at 12:46 PM, Brent Hilpert <hilpert at cs.ubc.ca> wrote:
> Well, the unit here was in pretty good physical condition as received.
> It had a cascading failure in the capstan driver but it was a fairly
> straightforward fix.
> I think there was one sluggish/partially-seized pulley bearing (freed up
> with some oil).
> Pretty rugged drives as you know. I wonder about the capstan rubber in the
> long term but I think that's about the only thing to worry about on age
> alone.
> I think bitsavers nowadays has manuals and schematics for the B version as
> you have, years ago I had to do some reverse-engineering for the capstan
> repair.
> This page is over ten years old and needs some updating, but FWIW:
> 	http://www.cs.ubc.ca/~hilpert/e/HP21xx/HP2116CSys/index.html
> Note the tape drive repair log page linked there.

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