WP34s: IDIV and the stack

[Dieter]

I am currently experimenting with some calendar routines on the 34s where the IDIV command often comes in handy. Since these routines are supposed to work with four as well as eight steck levels I checked them in either mode. This is where I discovered an unexpected behaviour of the IDIV command. With SSIZE 8 set, register T seems to get copied down to Z as the stack drops while the higher levels A to D do not change at all – just as it would happen in SSIZE 4.

Example:
Fill the stack with eight values...

Code:

88 [ENTER] 77 [ENTER] 66 [ENTER] 55 [ENTER] 44 [ENTER] 33 [ENTER] 22 [ENTER] 11

=>   D: 88
     C: 77
     B: 66
     A: 55
     T: 44
     Z: 33
     Y: 22
     X: 11

...and then do an integer division:

Code:

[IDIV]

=>   D: 88                     D: 88
     C: 77                     C: 88
     B: 66                     B: 77
     A: 55      instead of     A: 66
     T: 44                     T: 55
     Z: 44                     Z: 44
     Y: 33                     Y: 33
     X:  2                     X:  2

In other words: IDIV does not seem to handle the stack correctly in SSIZE 8 mode.
I am using a physical 34s with firmware 3.3 3666 (including printer and timer support).

Dieter