helloworld.md

Hello World!

Print HELLO WORLD! after running SYS 828.

Code

100 *=$033c
110 ldx #$00
120 loop lda msg,x
130 jsr $ffd2
140 inx
150 cpx #$0c
160 bne loop
170 rts
180 msg txt "hello world!"

Modification

Add an END label to mark the end of the message and calculate the message size during assembly. Then change the message to display whatever you want.

...
150 cpx #end-msg
...
190 end=*

Alternative version

Print all bytes from the MSG address until it encounters a zero byte.

100 *=$033c
110 ldx #$0
120 loop lda msg,x
130 beq stop
140 jsr $ffd2
150 inx
160 jmp loop
170 stop rts
180 msg txt "hello other world!",$0