Re: [cc65] Apple 2 ASCII with MSB on

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From: Justin England (jengland_at_enetis.net)
Date: 2003-05-14 01:30:10 

On Tue, 13 May 2003, Ullrich von Bassewitz wrote:

>
> Hi!
>
> On Mon, May 12, 2003 at 11:36:03AM -0400, Greg King wrote:
> > What Uz needs to know is:  what is created when Apple BASIC interprets
> > these statements?
>
> Yes, that is exactly the information I would need. Do you get these codes also
> when polling the keyboard, or are these codes just used when writing to screen
> memory?
>
I whiped up the following quick program:
.org    $6000
.define         EQU     =

RdKey           EQU     $FD0C	; ROM routine to read keyboard
PrByte          EQU     $FDDA	; ROM routine to print A in HEX
COut            EQU     $FDED	; ROM routine to print character in A
CROut           EQU     $FD8E	; ROM routine to print a CR

GetChar:
                jsr     RdKey
                pha
                jsr     PrByte
                lda     #$20
                ora     #$80	; if high bit not set, space is inversed
                jsr     COut
                pla
                jsr     COut
                jsr     CROut
                jmp     GetChar

Here is what I get:

E1 a
C1 A
E2 b
C2 B
E3 c
C3 C

etc.

It looks like all keyboard entry has the high bit set.  I will do some
digging and find where Applesoft stores it's BASIC programs and look to
see how characters are stored.

Also, In looking at some of the source listings in my //c tech ref manual,
they will always OR the character sent to COut with $80.

I will keep diggin to see what I can find.

Thanks,

Justin


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