Re: Changing the ASCII characters

[Rubywand <rubywand@swbell.net>]

David Wilson writes ...
> 
> Rubywand <rubywand@swbell.net> writes:
> 
> >Hector Gonzalez writes ...
> >>  Somebody knows how to changing the ASCII characters in the APPLE IIe or in
> >> a Multitech MPF-III, for example, I need to change the @ for a character
> >> that I invented.
> 
> >     As Nathan observes, what you want to do is swap in a custom
> >character generator PROM for your Text display. We did this when the
> 
> >     Doing your own character generator PROM (called the "Video ROM" on
> >a IIe) should not too be difficult. It looks like you'd use a 2732 or
> >2532 PROM.
> 
> Watch out - the 2532 has a different pinout to the 2732.

     Darn. In fact, aside from having A11 in the wrong place, the 2532
has just a single pin for /Chip Select and /Output Enable whereas the
IIe circuit uses the 2732's separate /CE and /OE pins. (Sorry about
that.)

>  Apple uses 2732
> (EPROM) or 2332 (ROM) chips in NTSC //e (and 2764/2364 in PAL //e).
> 
> For more information on the CHARGEN ROM, read Jim Sather's "Understanding
> the Apple //e". ....
>

     I'll be sure to if I can find it.

     One question: The standard (non-international) IIe/Enhanced IIe
diagram shows pin 21 (A11) going to a "GR" signal. Does this mean half
the PROM is just filled with 1's to output when Graphics are ON or does
it select mouse text characters (or what)?


Rubywand