grin

@anders @nthcdr lda #0 ; Load accumulator with character code for NULL
sta $0400 ; Store it in the screen memory to clear the screen
ldx #0 ; Initialize X register to 0
loop lda message,x ; Load the next character from the message
beq done ; If the character is NULL (end of string), we are done
sta $0400,x ; Store the character in the screen memory
inx ; Increment X register
bne loop ; Branch back to the loop
done rts ; Return from subroutine
message .text “Hello World!”,0 ; Null-terminated string