Oh yes, you are right. My apologies to everybody who attempted to "solve" this.

This is the result of retyping rather than copy/pasting a code (I was originally written it in a rather old laptop, and could not find the external diskette unit to move it to the comp from where I can connect to internet).

However, there is no need for a mul, a swap does it:

Quiz:
   mov   b,#16
   mul   ab
   rlc   a
   jb    p,Quiz1
   jz    Quiz2
   mov   a,#2
   sjmp  Quiz2
Quiz1:
   addc  a,#22h
   jc    Quiz2
   anl   a,#03h
   dec   a
Quiz2:
   addc  a,#0
   xch   a,b
   swap   a
   rlc   a
   jb    p,Quiz3
   jz    Quiz4
   mov   a,#2
   sjmp  Quiz4
Quiz3:
   addc  a,#22h
   jc    Quiz4
   anl   a,#03h
   dec   a
Quiz4:
   addc  a,b
   ret

This reminded me of an incident back at the university, when in a circuits exam the assistant who draw the questions on a blackboard forgot to copy out one resistor from his papers. This was some weird 3-phase system and nobody from the cca 30 students could solve it. In the afternoon when they gathered together for the oral part of exam, the professor was late some one hour, and when he finally came, he apologized and said, that for that one hour the whole staff of the electronics department tried to solve that "modified" circuit and they concluded that it IS unsolvable... :-)

JW