Another peculiarity (not multiline!)

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ecsfang
Posts: 51
Joined: Sun Jan 26, 2020 5:21 pm
Location: Lund/Sweden

Another peculiarity (not multiline!)

Post by ecsfang »

Hi!

Well, I wouldn't call this a bug, but it migh appear as one ...

Enter a short program:

Code: Select all

01 LBL 01
02 "ABCDEFGHIJKLMNO"  (ie a full text-string)
03 +
04 END
Stay in PRGM-mode, but change to display-mode (SA+X-reg) - ie not multiline mode.
Now, step through the program using "arrow up", and when line 02 is shown, step again while the line is still scrolling.
Depending on timing, how quick or for how long you press and the alignment of the planets, three things can happen:
  • You end up on line 01 (expected - this is what we wanted)
  • You are still on line 02 (normally no stepping is allowed while line is scrolling)
  • And sometimes you end up on line 03 (ie [SST] was executed instead of [BST])
What happens is that [SHIFT] is not activated while the display is scrolling (that is HP41 behavior - so correct) - and the "arrow up" (which is actually executed as [SHIFT]+[SST]) is then sometimes treated as a single [SST] - the [SHIFT] is "missed/dropped".

If you press [SHIFT] on a HP41 while the display is scrolling - the shift is ignored and the scrolling aborted and the text is rightaligned. And if not handled correctly on the DM41X, "arrow up" would always lead to a [SST], but there is some glitch that somtimes allows this to happen.

So if you time this right, pressing "arrow up" at the right time, you will never be able to backstep up to the beginning of the program - you will just jump between line 03 and 02 ... not likely but possible ;)

Cheers,
Thomas
[35/45/55/65/67/97/21/25/29C/31E/33E/38E/41C|CV|CX/71B/10C/11C/15C/16C/32SII/42S/28S/48GX/49G/35S/DM41X(#00456)]
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EM41
Posts: 192
Joined: Mon Mar 30, 2020 12:10 am
Location: Overijssel Netherlands

Re: Another peculiarity (not multiline!)

Post by EM41 »

i tried to see if i could reproduce the different modes of behaviour.
If you use arrow up at exactly the moment the display displaces you end up on line 03.
If you time in between two displacements you end up on 01.
The mode where nothing happens I cannot reproduce and there is a good amount of randomness in all of this.
HP41C (2x), HP41CV, HP41CX, DM41X β, DM41X, DM42, HP11C, HP48G, HP97
ecsfang
Posts: 51
Joined: Sun Jan 26, 2020 5:21 pm
Location: Lund/Sweden

Re: Another peculiarity (not multiline!)

Post by ecsfang »

Yes, the third resultat (just aborting the scrolling, and no change of line) is much more seldom, but happens now and then - if you are stubborn enough :geek:
If you try in SLOW mode, then it is even more frequent (feels like hitting the exact timing between the scrolling of the characters).
[35/45/55/65/67/97/21/25/29C/31E/33E/38E/41C|CV|CX/71B/10C/11C/15C/16C/32SII/42S/28S/48GX/49G/35S/DM41X(#00456)]
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