Int 21H, AH=44H, AL=02H

2 and higher

READ FROM CHARACTER DEVICE CONTROL CHANNEL

AX = 4402h
BX = file handle referencing character device
CX = number of bytes to read
DS:DX -> buffer

CF clear if successful

    AX = number of bytes actually read
CF set on error
    AX = error code (01h,05h,06h,0Dh) (see #01680 at AH=59h/BX=0000h)

format of data is driver-specific
  (also see separate entries below for some specific cases)
this function was not supported by Digital Research's DOS Plus

AX=4400h,AX=4403h“DOS”,AX=4404h“DOS”,INT 2F/AX=122Bh

Text based on Ralf Brown Interrupt List Release 61