HP 21MX toggle-in programs?

From: Jay West <jwest_at_classiccmp.org>
Date: Sun Jan 23 22:11:25 2005

> The next question: is there some sort of 'user guide' that shows how to
> operate the frontpanel to deposit/examine values in memory, etc? I've
> figured out how to get the program counter, and step through
> instructions (and the run/halt switch), but don't really know what the
> other registers/stuff is.

I can't believe the 21MX M or E user guide isn't online, but I don't see it
anywhere. You'll definitely need that book!

A = General purpose register A (also hardwired to location 0)
B = General purpose register B (also hardwired to location 1)
P = Program Counter
M = Memory register (points to whatever memory location is currently being
T = Target register (contains the contents of whatever location is pointed
to by M)
S = S register (display register) the front panel lights :) Accessible as a
device as well

So to put a halt into location 100... select M register, enter 100, hit
store, select T register, enter 102077, hit store.

One handy tidbit... if you have the T register selected and hit store, the M
register is automatically incremented by one for you.

To execute the halt instruction, select P register, enter 100, hit store,
preset, and run. You should get a 102077 halt.

Now on the 2100 front panel, you don't have to hit store at all. There's no
store button :)

Received on Sun Jan 23 2005 - 22:11:25 GMT

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