HelpPC 2.10 Quick Reference Utility Copyright 1991 David Jurgens

                INT 21,44,4 / IOCTL,4 - Read from Block Device


       AH = 44h
       AL = 04
       BL = drive number (0=default, 1=A:, 2=B:, 3=C:, ...)
       CX = number of bytes to read
       DS:DX = pointer to data buffer


       on return
       AX = number of bytes read if CF clear
          = error code if CF set  (see DOS ERROR CODES)


       - block drivers are not required to support this function
       - returns AX = 01 (invalid function code) if not supported

Esc or Alt-X to exit int 21,44,4 Home/PgUp/PgDn/End ←↑↓→