Int 5B  C - Ti Professional Pc - Keyboard Mapping Hook                     [b]

   CF set
   AH = shift state (see #2918)
   AL = scan code (see #2885)

Return:    BX, CX, DI, ES may be destroyed
   various return methods are supported:
       IRET, AX unchanged: process keystroke normally
       IRET, AL = FFh: discard keystroke
       IRET, AX changed: process modified keystroke
       chain to old INT 5B: allow other handlers to look at (possibly
         modified) keystroke in AX
       RETF 2, CF clear: place returned AX into keyboard buffer without
         any further processing

Notes: invoked by the keyboard ISR, and used to remap the keyboard
   if CF is clear on entry, some other handler has processed the
     keystroke and the current handler should not modify it, instead
     performing a RETF 2 or IRET (after clearing CF on the stack)
   when requesting that a value be placed directly into the keyboard
     buffer, AL and AH may not *both* be nonzero (the TI does not
     return scan codes as part of the key code for non-extended keys)

See Also: INT 15/AH=4Fh,INT 4A/AH=00h"TI",INT 59"TI Professional"

See Also: INT 5C"TI Professional",INT 5D"TI Professional"

See Also: INT 5E"TI Professional",INT 5F"TI Professional"

Bitfields for TI Professional PC keyboard mapping hook shift states:
Bit(s) Description (Table 2918)
 7 CAPS LOCK is on
 6-4   reserved (0)
 3 repeated key
 2 Shift is pressed
 1 Alt is pressed
 0 Ctrl is pressed