HP41 backarrow to CLX behavior

[Harald]

(07-25-2016 11:17 AM)Dieter Wrote:  

(07-24-2016 07:34 PM)hth Wrote:  I discovered a strange behavior in the HP41 digit entry and wonder if this is a bug.

I don't think so.

(07-24-2016 07:34 PM)hth Wrote:  Start digit entry :
3_

Press and hold <- (until NULL)
Gives 0

Sure. You entered a number and then deleted all of its digits by pressing the backspace key. This leaves an "empty value" in X, i.e. a zero. The CLX function was not executed (because keeping the key pressed has NULLed it) so there is stack lift is enabled. However, pressing the backspace key has removed the last (here = only) digit, so all that remains is a plain zero.

Dieter

I am not convinced the behaiviour is intentional.
Lets simplify things a bit
for example you have

Code:


Z: 1
T: 2
Y: 3

You now enter a number into x, a 5 for example.

If you then press the back arrow once (and get a zero) and follow this up with a 4, you end up with

Code:


Z: 1
T: 2
Y: 3
X: 4

But if you press and hold the back arrow after entering the 5 you get a "CLX", followed by "Null". To me that would mean that no function has been executed. Yet, if you now enter a 4 you get this:

Code:


Z: 2
T: 3
Y: 0
X: 4

Clearly the back arrow has been executed, and then clx has not been executed.
(Now that I have written all that, I realise that is just what you said Dieter ;-))

But the question is, why do we get the annulled "CLX"?
If you have entered more then one digit, say you have entered 56, and then press and hold the back arrow, the 6 gets deleted, leaving the 5. Nothing else happens. Why is that different when deleting the last digit?

Harald