[A83] Re: TI-83 Symbols
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[A83] Re: TI-83 Symbols
>
> > Not completely sure about this, but you could just add
> $80 to the first
> > char. If I remember correctly that would make all "valid"
> chars "invalid".
> > Extra benefit is that you only need one routine, since
> hiding is the same
> > thing as unhiding.
> >
> I'm not sure about this. One way to hide programs is to
> change the first char to "(", which is certainly a
> printable char, below ascii-128 (more exactly it's $28).
>
> PG
>
A "valid" program name has to start with "A", "B", ... ,"Z" or
theta. That are ASCII values 65 ($41) through 91 ($5B).
When you add $80 to a "valid" first char you get values in
the range 193 ($C1) through 219 ($DB). Those values are
all "invalid" (stuff like greek letters, super scripted letters,
and the like).
If you would add $80 to some ASCII value and the result
is $28, then before it was $28 + $80 = $A8. ASCII 168 is
(at least in the 83's character set) a lower case "o" with
a hat (btw, in standard ASCII that's 244, "ô"). If you hide
a program the first char could never become "(", because
then it would have been hidden to begin with.
Rob van Wijk
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