Re: IIe Keyboard On A II Plus

[David Wilson <mcs6502@gmail.com>]

On Jun 25, 1:46 pm, "Michael J. Mahon" <mjma...@aol.com> wrote:
> Actually, it's a single AND instruction that can be NOPed...
> But most users do not have the flexibility of being able to
> modify their monitor ROM.  (It may also require checksum
> compensation to keep picky software happy.)

Correct. Looking at my copy of the Red Book, the conversion to
uppercase is labeled CAPTST and looks like:

FD7E C9 E0      CMP #$E0
FD80 90 02      BCC ADDINP
FD82 29 DF     AND #$DF

So not only does it convert a-z to A-Z, it also maps `{|}~ and DEL to
@[\]^_

You can either convert FD83 to FF or FD82/3 to EA EA.