Int 2F Fn FD12  - Ks/keystkct.exe - Installation Check                     [K]

   AX = FD12h

Return: AX = 0093h if installed
       ES = resident code segment
       ES:CX -> internal "putbuf" routine
Program: KS/KEYSTKCT.EXE is a key stacking utility (4DOS KEYSTACK.SYS
     look-alike) by Martin Gerdes, published in c't 11/1991, which can be
     loaded as a device driver or as a TSR. It does not emulate 4DOS
     KSTACK API

Note:  the default buffer size is 128 keys