Int 14 Fn 0D  - Digiboard Digichannel Pc/x* - Get Pointer To Ch_key_rdy F  [S]

   AH = 0Dh
   DX = port number (00h-03h) (04h-43h for XAPCM232.SYS)

Return: ES:BX -> CH_KEY_RDY flag (see #0265)

See Also: AH=0Ah"Digiboard"

(Table 0265)
Values for Digiboard CH_KEY_RDY flag:
 00h   receive buffer empty
 FFh   characters available