HelpPC 2.10 Quick Reference Utility Copyright 1991 David Jurgens

                         Device Request Header Format

    Offset Size                Description

       00   byte       length in bytes of the request header
       01   byte       unit code;  the sub-unit the operation is for (block
                       devices);  meaningless for character devices
       02   word       command code, (see DEVICE COMMANDS)
       04  8bytes      reserved for DOS
       0C  nbytes      request data  (variable length)

       - see  INT 21,44  or    DEVICE ATTRIBUTES  or  DEVICE CODES
       - see also  IOCTL,n where "n" is an IOCTL function

Esc or Alt-X to exit device request headr Home/PgUp/PgDn/End ←↑↓→
Converted to HTML in 2006 by Timo Bingmann