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hp46 with strange modification
06-28-2022, 06:01 PM
Post: #1
hp46 with strange modification
Today I got a hp46 in good working condition. Obviously someone has changed the SIN and the COS key in a very professional manner (see pictures).

   

On the back of the calculator a centronix-port has been installed.

   

Inside the calculator a professional-looking PCB has been installed back to the keyboard. The flat band cable from the main PCB to the display is routed through this new PCB, which looks very professionally made. Unfortunately there is no visible label or any indication to the manufacturer.

   

   

The START X/S key (former SIN) shows a cyclic behaviour: it either stores the x-register into REG 4, into REG 3, into REG 9 or clears the x-register. Function of KORR (former COS) is unclear. I assume this modification allows for data transfer via the centronix-port.

Because this mod looks very professional I assume it has been made more than once: does anyone have more information about this modification ?

Roland


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06-28-2022, 06:30 PM
Post: #2
RE: hp46 with strange modification
Very interesting. Lots of 7400 series logic with 1975, 1976 date codes. There is one oddball chip in a ceramic package. It is hard to make out the part number but it looks like 'IM5623' which is a 256x4 PROM. Perhaps a character code lookup for the printer output?
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06-28-2022, 06:35 PM
Post: #3
RE: hp46 with strange modification
(06-28-2022 06:30 PM)Jeff_Birt Wrote:  ...There is one oddball chip in a ceramic package. It is hard to make out the part number but it looks like 'IM5623' which is a 256x4 PROM. Perhaps a character code lookup for the printer output?

the full label is "IM5623 CJE i (=Intel ?) Singapore 7632"

Roland
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06-28-2022, 11:43 PM (This post was last modified: 06-28-2022 11:43 PM by teenix.)
Post: #4
RE: hp46 with strange modification
KORR might be Keyboard OveRRide.

Maybe SIN COS work on alternate keypresses of this key.

cheers

Tony
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06-29-2022, 05:01 AM
Post: #5
RE: hp46 with strange modification
(06-28-2022 11:43 PM)teenix Wrote:  KORR might be Keyboard OveRRide.

Maybe SIN COS work on alternate keypresses of this key.

cheers

Tony

Unfortunately not. I tried every possible combination (longer press, combined press etc) - it stays with the modified behaviour.

Meanwhile I examined the modification further: the backside of the PCB says "EPIS - HP 75-000L". The traces on the keyboard-PCB to switches SIN and COS are cut and separate wires are going to the modification. A few separate wires are going from the modification to the power supply and to the logic board.

I'm going to document this modification carefully and then I will try to bring the calculator back to its original state.

Roland
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06-29-2022, 06:18 AM
Post: #6
RE: hp46 with strange modification
(06-28-2022 11:43 PM)teenix Wrote:  KORR might be Keyboard OveRRide.

From the back label STAATLICHE INGENIEURSCHULE AALEN LANDESEIGENTUM I assume that could be an abbreviation for KORREKTUR (correction).
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06-29-2022, 09:23 AM
Post: #7
RE: hp46 with strange modification
(06-29-2022 06:18 AM)Thomas Klemm Wrote:  
(06-28-2022 11:43 PM)teenix Wrote:  KORR might be Keyboard OveRRide.

From the back label STAATLICHE INGENIEURSCHULE AALEN LANDESEIGENTUM I assume that could be an abbreviation for KORREKTUR (correction).

Yes, KORR may be short for German "Korrektur".
I contacted Hochschule Aalen, but there is no further information available.

In the web I found a German Company "Epis GmbH", specialized (among others) on industrial electronics. Maybe this is the manufacturer.

Meanwhile I removed the modification and repaired a few changes they made on the keyboard PCB. Now the hp46 is in its original state and working fine.

If someone has spare SIN and COS keys I would be happy to get them to remove the last signs of this modification :-)

And a final question: why has the hp46 a red/black printer ribbon ? I could not find any hint how to let it print in red !

Roland
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06-29-2022, 11:20 AM
Post: #8
RE: hp46 with strange modification
(06-29-2022 09:23 AM)Roland57 Wrote:  And a final question: why has the hp46 a red/black printer ribbon ? I could not find any hint how to let it print in red !

Negative numbers are printed in Red as indicated in the manual page 7:

Negative Numbers
To key in a negative number, press CHS (change sign) after keying in
the positive value. Negative numbers are printed in red.


and as visible here.
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06-29-2022, 12:12 PM
Post: #9
RE: hp46 with strange modification
thankyou, now it works. I tried it before without any success, I don't know what I did wrong

Roland
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06-29-2022, 02:09 PM
Post: #10
RE: hp46 with strange modification
Hello!

(06-29-2022 09:23 AM)Roland57 Wrote:  If someone has spare SIN and COS keys I would be happy to get them to remove the last signs of this modification :-)

I know that I have a broken HP46 somewhere that I bought for spare parts (but I also have a working one that still has an inventory sticker of the "Bundesnachrichtendienst" on it, the german secret service, and I always wondered what they used it for). If I find it and the keycaps are still there you can have them.

Regards
Max
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06-29-2022, 02:33 PM
Post: #11
RE: hp46 with strange modification
Fascinating!

Vintage HP handheld user
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06-29-2022, 07:59 PM
Post: #12
RE: hp46 with strange modification
(06-29-2022 02:09 PM)Maximilian Hohmann Wrote:  Hello!

(06-29-2022 09:23 AM)Roland57 Wrote:  If someone has spare SIN and COS keys I would be happy to get them to remove the last signs of this modification :-)

I know that I have a broken HP46 somewhere that I bought for spare parts (but I also have a working one that still has an inventory sticker of the "Bundesnachrichtendienst" on it, the german secret service, and I always wondered what they used it for). If I find it and the keycaps are still there you can have them.

Regards
Max
Hello Max, that would be sooo great ! I hope you'll find them,

regards
Roland
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