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HP Forum Archive 14

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Message #1 Posted by Matthias on 4 Oct 2004, 5:22 a.m.


Just before I got a second ERAMCO ESMLDL 1 EPROM box. I compared it with my old one and was wondering. One is in a plastic case, the other in a metal box with about half the high. Both have the same Label on it, expect the bigger plasic case has also a "Eramco Systems" label. Both are the same type ES 83120A. I opened the boxes. The plastic box contains three circuit board, some additional dips and a backup battery. The metal box contains two dark green circuit board and no bacpup battery. Here the EPROMS with the Sytsems are installed, but CAT2 does not shows anything.

Any ideas?

Yours Matthias

Message #2 Posted by Ronald on 4 Oct 2004, 8:31 a.m.,
in response to message #1 by Matthias

The Eramco story is as follows:

At first Arne Luhrs (works now at HP France) made a wirewrap version based on the original ideas as described in the PPC Journal.

Later 3 people met each other at "Prins kantoorboekhandel" in Delft decided their to start Eramco. Prins Kantooboekhandel was at that time a HP dealer and partner.

Prins Kantoorboekhandel had a customer (Has Konings: enginering copmpany) who had ordered custom made modules but unfortunately they had an error, so very nice modules but unusable. This question was asked to the above mentioned 3 people who took the challenge to produce EPROM boxes. For that the production proces was first done very primitive by making the printed circuit boards themselve (lightning, etching etc.) This was no good at all, so this was outsourced to a professional print maker in Belgium. The next trouble was getting a right size box. Off course this was not available when you do not design for it, nor was there money to have it custum made in plastic. So metal boxes were bought and a small firm in Amstelveen/Ouderkerk aan de Amstel in the Netherlands was able to paint them black. The needed connectors were gotten from USA contacts via ad's and the other activity Eramco did "combining modules and building modules inside the HP 41 itself.

The box you have is one of that first series. If I remember correctly there were +/- 100 ofthat of boxes produced (2 circuit boards, one for the Eproms, one for the logic)

After that there were others, like the MLDL with bankswitchable RAM ( you have on your website, there were 2 versions, one with the bankselect rotary switches for the RAM at the top, so you could adjust when the box was closed and one with all the swithes on the inside) and also a pure EPROM version with 2 * 32K eproms (You have 6 * 4K eproms). That one was designed to fit in a small box and had only circuit board needed. Here were 3 circuit boards, one with the epromns, one with the logic and one with RAM chips and logic belonging to that.

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