Int 16 Fn A2  - Keyb.com Keyboard Capabilities Check (not An Actual Funct  [K]

   AH = A2h

Return: AH <= 80h if 122-key keyboard functions (AH=20h-22h) supported
Desc:  this function is called by the DOS 3.2 KEYBxx.COM and DOS 5+ KEYB.COM
     to determine the highest supported keyboard function

Note:  many BIOSes (including at least some versions of Phoenix and AMI) will
     destroy AH on return from functions higher than AH=12h, returning
     12h less than was in AH on entry (due to a chain of DEC/JZ
     instructions)

See Also: AH=05h"PCjr",AH=92h,INT 2F/AX=AD80h