I would appreciate comments on my code. It prints a blue "A" in the upper left corner of the screen. It should work on expanded/unexpanded vic.
I'm using dasm/VICE on a mac. I invoke this with SYS4608.
Am I doing anything dumb? Thanks!
Code: Select all
processor 6502
org $1200
; set up vic-20 screen memory address at $0-$1.
LDA #$0
STA $0
LDA $0288
STA $1
; set up color memory address at $2-$3.
LDA #$0
STA $2
LDA $9002
EOR #$80
BNE .1
LDA #$94
JMP .2
.1 LDA #$96
.2 STA $3
LDY #$0
LDA #$1 ; screen code for "A"
STA ($0),Y ; set screen code
LDA #$6 ; color code for blue
STA ($2),Y ; set color code
RTS