Would the HP-15C Limited Edition Firmware Age Away?

[teenix]

(03-19-2018 07:54 PM)Greg Wrote:  Now, if you'd done what you did but pressed 4 divide before switching to WPRGM, you would have been even more confused. I was sure I'd done something seriously wrong the first time I tested that on the HP-65 emulator.

You'll see "81" in the WPRGM display and that isn't in the program.

The HP-65 puts all key press values into a buffer and when switched to W/PGM this value is added to the program counter with the Buffer -> ROMaddress instruction. This causes a jump to a ROM address determined by the buffer value. Its function is to display a keyboard coordinate, and in this case the last key pressed.

This buffer also gets filled with the current program step when a program is running or by using SST etc, which is why the keyboard position of the current program step appears.

cheers

Tony