----- Original Message -----
From: "Marko Mäkelä" <msmakela@cc.hut.fi>
> Oh, now I got it: you use the zero page or stack page relocation register
> and write the data to $100-$104 or to $00-$04 (well, I guess it's easier
> for you to write to $100 or $101 than to $00 or $01 (I've done the latter
> without using the MMU)).
>
Marko-
I like the idea. I was wondering if the zero page relocation register would
work for $00 and $01 of the $ff00/$ff01 registers? According to my Mapping
the C128, all references to $00 and $01 would go to the true $00/$01 of the
8502's I/O ports. I think that the following code would not work:
lda #value
sta $00 ; sta $ff00
lda #value
sta $01 ; sta $ff01
But, would the following code work?
ldx #$01
lda #value
sta $ff,x ; sta $ff00
inx
lda #value
sta $ff,x ; sta $ff01
By indirectly accessing $00 and $01 using the wraparound feature of the 65xx
CPU, would this method work with a relocated zero page in a C128 system?
If that doesn't work, then the relocatable stack should work in accessing
the ram underneath $ff00-$ff04.
Thanks,
-Todd Elliott
Message was sent through the cbm-hackers mailing list
Archive generated by hypermail 2.1.1.