V41 and its display functions
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05-08-2016, 03:56 PM
Post: #1
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V41 and its display functions
For quite a while I have been using V41 ("Release 8"), and I always wondered why, unlike the "real thing", the display functions FIX, SCI and ENG prompt for a two-digit entry, i.e. FIX shows two underscores, like a STO or RCL. And indeed you can enter the same parameters as with the storage-related commands: FIX 35 or even SCI X are accepted without an error message. But what does this do?
After trying some commands like FIX 20 or SCI 99 it turned out that obviously not only the display-related settings were affected, but also the angular mode which is stored in the following flags. In case you forgot about this: On the '41, the four bits represented by flag 36...39 hold the number of digits, flag 40 is set in FIX mode, flag 41 in ENG mode (both clear means SCI), and flag 42 is set in GRAD resp. flag 43 in RAD (both clear means DEG). So it looks like this: Code: Display Digits FIX ENG GRD RAD For example: Code: Display Digits FIX ENG GRD RAD Here the calculator is set to FIX 5 and Radians mode. Now what does a command do that is not possible on a real hardware HP41? For instance FIX 20, which can be entered on V41 without a problem. I wrote a short program that displays the status of flags 36...43, and here is what I got: First of all, let's assume FIX 4 and DEG mode. This yields... Code: Display Digits FIX ENG GRD RAD What about FIX 15? Code: Display Digits FIX ENG GRD RAD Now for the interesting part. I tried a FIX 20 command: Code: Display Digits FIX ENG GRD RAD From the entered 20 (=10100) the four lowest bits are stored in flag 36...39, and the excessive MSB obviously has spilled into the angular mode section, so that this command turned on Radians mode! Even more interesting: let's see what a few consecutive FIX 20 commands will do: Code: FIX 20 => This is FIX 4 with Grad mode turned on! Code: FIX 20 => One more time: Code: FIX 20 => Until here it looks like each successive FIX 20 counts up the four-bit number in F40...F43 (or at least the three bits in F41...F43). But then, do one last FIX 20: Code: FIX 20 => This is the same result as a few steps before. BTW, if you tried this on V41, be sure to reset its settings to normal by a DEG and FIX 04. So this means:
I have not yet figured out what's exactly happening here inside V41, but I think all this has to be considered a bug that should be corrected. What do you think? Dieter |
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Messages In This Thread |
V41 and its display functions - Dieter - 05-08-2016 03:56 PM
RE: V41 and its display functions - Massimo Gnerucci - 05-08-2016, 04:18 PM
RE: V41 and its display functions - Dieter - 05-08-2016, 04:48 PM
RE: V41 and its display functions - Massimo Gnerucci - 05-08-2016, 06:28 PM
RE: V41 and its display functions - Ángel Martin - 05-09-2016, 05:05 AM
RE: V41 and its display functions - Dieter - 05-09-2016, 07:39 AM
RE: V41 and its display functions - Ángel Martin - 05-09-2016, 10:45 AM
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