Free42 Version 3

Discussion around the Swiss Micros DM42 calculator.
Thomas Okken
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Re: Free42 Version 3

Post by Thomas Okken »

Walter wrote:
Sun Feb 28, 2021 6:37 pm
automatic stack lift
What are you referring to here?
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Walter
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Re: Free42 Version 3

Post by Walter »

Thomas Okken wrote:
Sun Feb 28, 2021 7:07 pm
Walter wrote:
Sun Feb 28, 2021 6:37 pm
automatic stack lift
What are you referring to here?
Please look up the HP-42S Owner's Manual, p. 45, or the WP43S Owner's Manual, pp. 34f, or the WP34S Owner's Manual, p. 39.
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Thomas Okken
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Re: Free42 Version 3

Post by Thomas Okken »

And which calculators we were talking about here do not possess this feature?

UPDATE: Argh, I should have pushed harder here. Now it may look as though Walter wasn't spreading nonsense about Free42.
Just to be clear: Free42 does have automatic stack lift, regardless of which mode it is in. Pointing out that the wp43 has this feature appears to have been meant to imply that Free42 in big stack mode doesn't, and that is not true.

Moderators, could you delete or at least annotate Walter's post to that effect? I don't think it's good manners to spread deliberate misinformation here.
Last edited by Thomas Okken on Mon Mar 01, 2021 10:30 pm, edited 1 time in total.
ringworm
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Re: Free42 Version 3

Post by ringworm »

Walter wrote:
Sun Feb 28, 2021 6:37 pm
This is debatable. Actually, we have shown with the WP34S that all real-world calculations can be done with just an 8-level stack at zero risk of stack overflow. We continue offering such a stack with the WP43S, keeping the benefits of RPN (automatic stack lift, top stack level repetition).
Technically you are right. 40 years we have 4 stack levels and that was ok. Having 8 will do much more.
But unlimited stack is not just a very large stack. This is a very different technique of programming, not reachable with limited stack of any size.
IMHO WP43S placement slightly differs from free42. Thus it cannot be used as representative example of usefulness of unlimited stack. I think having a stack more than 4 for HP 41 is really wrong idea. That machine benefits of such short stack. But for DM42 it is really good to have such opportunity, especially if it can be dynamically switched
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Re: Free42 Version 3

Post by toml_12953 »

Walter wrote:
Sun Feb 28, 2021 6:37 pm
This is debatable. Actually, we have shown with the WP34S that all real-world calculations can be done with just an 8-level stack at zero risk of stack overflow. We continue offering such a stack with the WP43S, keeping the benefits of RPN (automatic stack lift, top stack level repetition).
Maybe calculations can get by with eight levels but recursive function calls that put parameters on the stack will need many more than eight.
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Walter
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Re: Free42 Version 3

Post by Walter »

toml_12953 wrote:
Mon Mar 01, 2021 2:50 am
Walter wrote:
Sun Feb 28, 2021 6:37 pm
Actually, we have shown with the WP34S that all real-world calculations can be done with just an 8-level stack at zero risk of stack overflow. We continue offering such a stack with the WP43S, keeping the benefits of RPN (automatic stack lift, top stack level repetition).
Maybe calculations can get by with eight levels but recursive function calls that put parameters on the stack will need many more than eight.
Recursive functions are covered by local registers.
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ringworm
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Re: Free42 Version 3

Post by ringworm »

toml_12953 wrote:
Mon Mar 01, 2021 2:50 am
Maybe calculations can get by with eight levels but recursive function calls that put parameters on the stack will need many more than eight.
This is not too hard to implement without unlimited stack.
But there is a very powerful function which usually called MAP.
With unlimited stack it becomes real to create really awesome and powerful realization of that function. It can be the prime caliber gun to optimize really long vector calculations.
And normal implementation of MAP needs unlimited stack behavior. In fixed stack it wont go without plenty of extra stack checking code

Unlimited stack is a tool which cannot be replaced by fixed stack of any size. This is another behavior.
We have enough stack size of 4. Alas.
But unlimited stack is not for extending stack. Most of functions will continue using 2-3 stack parameters, but with unlimited stack they can be used in a very different way, which gives a huge gap of freedom for programmer, never seen in rpn systems.
Anyway unlimited stack brings no minuses, those who does not need it just does not used.
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Fg1969
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Re: Free42 Version 3

Post by Fg1969 »

I must agree: Unlimited stack size is no problem. In Version 3 there is the posibility to switch between both, 4 stack and unlimited stack size. I see no problems, only new ways of programming DM42/free42. Thomas Okken has done a very good job. Thanks !
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Re: Free42 Version 3

Post by HPMike »

The dynamic stack feature is great for the Free42 emulator, but it is even better on the DM42 with its multi-line display. This is why I urge the SM crew to update the DM42 with the new version 3 of Free42, even it there are no current updates for the DMCP OS or other DM42 features and bug fixes.
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amafan
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Re: Free42 Version 3

Post by amafan »

HPMike wrote:
Mon Mar 01, 2021 6:15 pm
The dynamic stack feature is great for the Free42 emulator, but it is even better on the DM42 with its multi-line display. This is why I urge the SM crew to update the DM42 with the new version 3 of Free42, even it there are no current updates for the DMCP OS or other DM42 features and bug fixes.
I'm in favor of updating the DM42 to the Free42 ver.3, if it doesn't create any backward compatibility issues with programs written for 4 level stack. Some of the programs I use depend on stack lift and its also one of the reasons RPN has been my choice in calculators for 40 years.

Moderator note: Free42 in big stack mode does not remove stack lift
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