The Museum of HP Calculators

HP Forum Archive 15

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Repairing HP-85's.
Message #1 Posted by Barrie Carruthers on 18 Dec 2005, 10:24 p.m.

Beleive it or not we are still using some eight odd HP-85's in our work place. One gets pretty slick at trouble shooting and refurbishing these neat little machines after a time but I am reaching the point where I have several otherwise perfectly good units except they requires an I/O ROM or the Video ROM, CPU perhaps and my spares box is starting to look pretty bleak. Any body have any ideas where these can be picked up or has anybody worked out a work around using a standard PROMs and adapters perhaps?

      
Re: Repairing HP-85's.
Message #2 Posted by Vassilis Prevelakis on 18 Dec 2005, 11:40 p.m.,
in response to message #1 by Barrie Carruthers

This board allows normal EPROMs to be connected to the HP Series 80 computers. It comes with a number of ROMs already stored in its EPROM, and you can add your own.

It is available from http://www.vintagecomputers.freeserve.co.uk/hp85/prm85user.htm

(and a small plug for my site) a lot of information on the Series80 computers may be found at http://www.series80.org

**vp

            
Re: Repairing HP-85's.
Message #3 Posted by Sunny on 19 Dec 2005, 4:36 p.m.,
in response to message #2 by Vassilis Prevelakis

What I make out of your response is that its a board that goes into the exapansion slot which is at the back of the machine. If the I/O rom is at fault, will this work?

In another words, does it automatically bypass all the bits viz, the video rom and the CPU? Thanks Sunny

            
Re: Repairing HP-85's.
Message #4 Posted by Barrie Carruthers on 19 Dec 2005, 11:17 p.m.,
in response to message #2 by Vassilis Prevelakis

Thanks for your helpful information and referral to your site Vassilis.

      
Re: Repairing HP-85's.
Message #5 Posted by Howard Owen on 18 Dec 2005, 11:50 p.m.,
in response to message #1 by Barrie Carruthers

85As amd 85Bs show up on eBay pretty frequently. They go anywhere from $35 to $125 depending on conditions and luck of the draw.

As far as PROMs go, there's a new hobbyist board called the PRM-85 that is an implementation of the EPROM ROM drawer. Only this updated version lets you have up to 8 ROM images in a single EPROM, all online at once. The card ships with a "SuperROM" containing the following:

 
  Advanced Programming
  Assembler
  Service-85
  Program Development
  Mass Storage 
  Matrix
  Input/Output
  Extended Mass Storage

These are all the 85 versioms, but an equivilant EPROM for the 86/87 has just been developed.

I can confirm that the device works great. I have it plugged in to my 85B, but I'm checking my mail for the 86/87 SuperROM, which John has sent me from England free of charge! (I am deeply impressed by that. 8)

It's a hobbyist device, which doesn't mean that it's of poor quality, quite the contrary. But there is one guy, the designer, building the boards. So I don't kmow what kind of volume he can handle.

Hope this was helpful
Howard

            
Re: Repairing HP-85's.
Message #6 Posted by john on 19 Dec 2005, 7:38 p.m.,
in response to message #5 by Howard Owen

Hi,

The PRM-85 boards are designed and made by Bill Koteska. Volume of boards made so far is around the 10 mark, we have hardly been overwhelmed with enquires so I suspect volume will stay in the 10s for some while yet.

There was a waiting list, but I understand everyone on it has now been supplied with or offered boards. One person on the list has pulled out, so I have one board and am looking for a buyer. The price is $100/€100 or £60 plus postage.

Please e-mail me if you are interested, and I will send further details or if there are more than one reply I'll start a new waiting list!

Regards, John

            
Re: Repairing HP-85's.
Message #7 Posted by Barrie Carruthers on 19 Dec 2005, 10:47 p.m.,
in response to message #5 by Howard Owen

Well thanks for this information Howard. Sounds a great concept. Will certainly follow it up. The ROM/Controllers I really need are the Video Controller, the Printer Controller and the I/O Controller - as distinct from the Input/Outout ROM These are the HP IC's Part no's:- 1MA5-0101,1MA9-0101,1MA8-0101.

Yes I do have the option to aquire additional 85's and I may have to do that. Unfiortunately that much harder being out in the sticks down here in New Zealand.

Thanks for your response

Barrie

      
Re: Repairing HP-85's.
Message #8 Posted by Howard Owen on 18 Dec 2005, 11:54 p.m.,
in response to message #1 by Barrie Carruthers

I see Vassilis beat me to the punch on the PRM-85. 8) Let me second the plug for his website. It's a great resource for HP-85 tips, software and documentation.

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