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

[david@uow.edu.au (David Wilson)]

Rubywand <rubywand@swbell.net> writes:
>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

The only problem with this change is that the ROMs in a ][ or ][+ are not
pin-compatible with EPROMs of the same size. Thus, to make this change you
would need to wire an adapter between the EPROM and the ROM socket to sort out
the chip select polarities.
--
David Wilson  School of IT & CS, Uni of Wollongong, Australia  david@uow.edu.au