10 REM TINY MAZE, 6502 VERSION
20 SYS {ASM_START}

        ;16-bit LFSR (RNG)
loop    lda seed
        lsr
        rol seed+1
        bcc noeor
        eor #$B4 
noeor   sta seed
        eor seed+1

        ;output character code 205 + least significant bit (LSB) from RNG
        and #1
        clc
        adc #205
        jsr $FFD2       ;call the print routine

        ;check for STOP key, loop if not pressed
        lda #9
        sei
        sta $E810       ;set up PIA1 PA to scan key row 9
        lda $E812       ;read keyboard column from PIA1 PB
        cli
        and #%00010000  ;is it column 4?
        bne loop
        rts

seed
        .byte $39
        .byte $D2