M Registers on early HP Calculators

[bshoring]

The M, M1 and M2 registers can be used as storage or as general purpose scratch pad registers to help the microcode out if it needs to temporarily store some data. The HP45 for example uses the M register to store the FIX SCI values when set by the user. In the HP97 this data is stored in RAM memory register $3E. The HP67 uses M1 quite a lot while executing various functions.

Not familiar with Voyagers.

cheers

Tony
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Thanks, Tony. I'll also be interested to see if any of the others have something to add.

Thanks!