I'm after a bit more information on the way the HP67, HP29, and HP25 machines behave when a key is pressed while a program is executing.
The HP33 and HP34 both simply stop executing the program and stop at the current instruction (even if it is a pause) and otherwise ignore the keystroke.
Unfortunately I can't check the behaviour of the other models myself.
I believe that an HP67 will execute the keystroke if pressed while a pause instruction is executing but can't remember what happens if a key is pressed while a program is running. I did have some information but can't find my old notes at the moment.
I suspect that behaviour of the HP29 may be the same as the HP67 as they are both similar but I have no idea what happens on an HP25.
I'd really like to know if my assumptions are correct and what really happens on these models both when a key is pressed while a program is running (including a label key or GSB) and when a key is pressed during a pause instruction.
It might be interesting to compare this to the behaviour of current models like the HP20b so see which scheme 'won'..
Thanks
Mike T.