HP-75D made for ATT


I have an HP-75D calculator made by HP with the AT&T nameplate. It has the expansion pod with 64K of memory and the modem ports, but the calculator itself only shows 22K free.

I have a 75C with manuals, but I can find no command to merge memory in the pod with that in the calculator. I have tried the port commands to no avail. Does anyone have a clue how to tell if the pod memory is any good and how to use it?

Also, does the calculator come out of the pod?

I picked this up pretty cheap, but I would still like to get the pod going.



The 64K of memory in the expansion pod is an "Electonic Disk" and not user memory. The device ID for the RAM Disk is :XMEM. To save a program to the pod you use:



If you want to remove the HP-75 then take out the four long screws in the base of the pod. However, with the HP-75 freed from the pod you'll find that the computer's battery cover has been removed in order to connect to the power supply in the pod. Unless you have a spare battery cover, you will have no way to keep the battery in place.

Mark Hardman

Houston, TX

Edited: 3 Jan 2004, 11:37 a.m.



Now the pod is sort of useful. I bought it on eBay for only about $15.00 (plus shipping), to get the pod and play with it. The calculator bezel has a number of cosmetic flaws, but otherwise it is in good shape. The batteries it came with go down in about 10-14 days.

I may take it appart to clean it up better, otherwise I have no need to, I was wondering about how it was attached to the base calculator.

I might now transfer my application modules to the "AT&T" and use for play leaving my real 75C and clean and safe.


Try typing the command "kubla khan" while your 75 is attached to the power pod. You may want to adjust the delay or better yet, output the display elsewhere (like a printer or a monitor).

I have heard that the designers intended to make the power pod's edisc capable of being merged but didn't get around to doing it. Therefore, there was some unused space in the power pod's ROM which was utilized for the above command.

I wonder if anyone ever wrote a lex file to extend the use of the 75 pod?

By the way, the MOHPC DVD has the manual to the expansion pod.



That is the coolest and maybe the oldest "Easter Egg" I have heard of!

I will print this out later!

Thanks for the tip!

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