HP 71b: Oregon Digital Environmental Case

[Michael Fehlhammer]

What I have found out so far:
Thanks to Dave I got a manual for a similar machine of Oregon Digital, s simpler version called "SerialPlus".
This might help when building a customized serial cable, for example ( because the pinout of the special 15 pin D SUB connector is described there, it it probably was not changed ).
In contrast to CMT's muticase, for example, the serial port and the LCD are not implemented as HP IL devices, therefore I need not plug in the IL cables to get the LCD alive ( see pictures ). The connection is made through the card reader port. For the serial port to work ( according to the manual for the simpler version without LCD, RAM and ROM ) special drivers are neccessary.
Probably special drivers are needed as well for this version, at least it wants to load something from somewhere immediately after being switched on.
I could find out that the device is equipped with 128 K of RAM (!), organized in 4 Ports (5.01 ... 5.04 ) of 32 K each. Port 5.02 cannot be freed, it is always part of main memory. Port 5 (5.00 ) hosts a 32k ROM.

Unfortunately I have big trouble with the power supply: Immediately after the pictures were taken, the calculator went off (shortly displaying a low battery warning ).
I had replaced the 5 NiCd cells by NIMH cells, which in many cases works and is even recommended.
The OD case seems to have emptied these precharged cells quickly.
Now I try to run the device from the power adapter plugged in, but mostly it doesn't respond at all.
Sometimes, after pressing and holding the ON key for a while, it shows the pictured "Welcome screen" on the additional 2-rows display.
Interestingly, the init-sequence ON / works reliably, but immediately after initializing the calculator shuts down.
I should have mentioned that the calculator is powered by the case ( via card reader port ) only, the batteries have been removed, as it is demanded in the manual.
If I only understood a little about electronics ... doesn't it sound as if there was some short curcuit on the OD board?

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