Re: II+ vs IIe Char Gen PROMs and Shift-key mods-- LC $F8 PROM mod

[Rubywand <rubywand@swbell.net>]

James Higginbotham wrote:
> 
> It's starting to all come back now...  I believe you are right, I don't
> remember ever typing anything at the BASIC prompt in lower case...  (means I
> need to dig out the II+ again)...  Is the mod you where talking about
> documented anywhere?
> 
 ....

     Not as far as I know. What you do is $EA out the code which does the checking.
The code starts at address $FD7E in both the old and Autostart Apple II+'s (which
should be address $57E in a 2K $F8 PROM) ...

FD7E- C9 E0  compare the byte to the lowest ASCII value for a lower case char
FD80- 90 02  if the byte is less (not lower case) hop over the next two inst bytes
FD82- 29 DF  if the byte is lower case AND it with #$DF to force upper case


     To get rid of the check and conversion you can substitute NOP instructions

FD7E- EA
FD7F- EA
FD80- EA
FD81- EA
FD82- EA
FD83- EA



Rubywand