Re: A83: 3 bits free in symboltable entry? [83]
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Re: A83: 3 bits free in symboltable entry? [83]
In accordance with the prophecy, Henk Poley uttered:
>
> Ti docs say that with programs/lists(/etc?) entries there are 3 bits for
> 'internal use'. Are they really used or are they free, and if they are
> used, what do they mean/ what's the purpose?
>
> Could they be used for directories like the on the Ti-85/86?
>
> Henk Poley
They are used. When you graph equations (i.e. when you hit the Graph key), TI-OS
marks all the equations it uses, as well as all the variables that these
equations refer to. It also marks them all as "unchanged". Then it clears the
graph buffer "dirty" bit.
When you press Graph again, TI-OS doesn't start drawing everything from scratch,
because the "dirty" bit isn't set.
But whenever you set a variable to something, the bits are altered, so the
variable is no longer marked as "unchanged". If the variable is part of an
equation that should be displayed on the graph screen, the "dirty" flag is set,
and pressing Graph involves drawing everything from scratch.
This procedure involves two of the three reserved bits. Someone else said the
third bit is used when selecting multiple variables in the link menu, which
makes sense.
So the answer is that they are all used.
Linus
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