c $CDAA sets alternate bytes of INBUF to $00 and $FF
C $CDAA point HL at INBUF
C $CDAD set loop counter to $9E (158 decimal)
C $CDAF set next two bytes of INBUF to $00 and $FF
C $CDB5 loop back to $CDAF 157 times
C $CDB7 return