rom dump of a 32Sii



#7

Is it possible to dump the rom of this machine? I know, it has not Ir, but is it possible?
Thanks.


#8

> but is it possible?

Possible? Yes.

Easy? No.

There are two approaches. One is to remove the chip, decapsulate the die using fuming nitric acid (sometimes mixed with sulphuric acid). Then a photomicrograph is taken, and the ROM bits should be visible. These chips are old enough that they aren't likely to have metal layers above the ROM. This is the method Peter Monta used to get the HP-35 ROM dump, except that the chip was in a metal can so he only had to saw the lid off rather than dealing with acids.

The other approach is to figure out how to get the part into a test mode in which the internal Saturn bus activity is visible on the package pins, then run the self-test, can capture the ROM data as it is checksummed. This is what I've done on the Spice and Voyager calculators, although with most of them the bus is always available. I have some but not all of the information necessary to do this to the 32SII.

However, if I were to extract the 32SII ROM by either method, I would still be unable to provide a copy of it to anyone. Unlike the Voyager and earlier calculators, HP did copyright the firmware of the Pioneer and Clamshell calculators.


#9

Thanks for your respnse, it seems very difficult.
but thanks

#10

A possible (from my arm chair) method would be to de-solder the ROM chip and put it in another circuit that reads each address in sequence.

You could build such a reading circuit using a simple micro or even the HP41 to control the address lines and reading the data lines.

The hardest part may be either re-soldering the ROM onto the new PCB or cleaning up the legs well enough to use a test socket.

Anyway this is probably a bit easier, quicker and safer than the acid and microscope method. Still not easy though, and HP own the copyright.


#11

Quote:
A possible (from my arm chair) method would be to de-solder the ROM chip and put it in another circuit that reads each address in sequence.

You'd need a much finer soldering iron than I've ever found. The ROM is buried inside the 1LR3 (Sacajawea) chip, along with the CPU, RAM, and display driver.


#12

Ah, I didn't remember that detail - thanks for the info. I'll have to get out of my arm chair more often...


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