!-u ip - 5
 0605:0728 B80010            mov     ax, 1000
 0605:072B CD2F              int     2F
 0605:072D A95553            test    ax, 5355
 0605:0730 C3                retn

 0605:2E9B E88AD8            call    0728
 0605:2E9E 3CFF              cmp     al, FF
 0605:2EA0 18C0              sbb     al, al
 0605:2EA2 FEC0              inc     al
 0605:2EA4 A2B20C            mov     [0CB2], al
 0605:2EA7 98                cbw
 0605:2EA8 C3                retn