Indeed! So how did you get in such a crazy mood to create this thing? Too much sugar? Caffeine? (c:

Following are a couple more subroutines that do the same thing as the (corrected) original. Neither of them is as wild and crazy as Jan's routine, but it's not completely obvious what they do, either. I have a third solution that is smaller than the one at Quiz6, but it is straightforward, so I won't spoil the fun by posting it just yet.

-- Russ

Quiz5:  mov     b,a
        anl     a,#85
        xch     a,b
        rrc     a
        anl     a,#85
        add     a,b
        mov     b,a
        anl     a,#51
        xch     a,b
        rr      a
        rrc     a
        anl     a,#51
        add     a,b
        mov     b,a
        anl     a,#7
        xch     a,b
        swap    a
        anl     a,#7
        add     a,b
        ret

; --------------------------

Quiz6:  mov     b,#0
        jz      Quiz8
Quiz7:  mov     r0,a
        dec     r0
        anl     a,r0
        inc     b
        jnz     Quiz7
Quiz8:  mov     a,b
        ret