Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!comp.vuw.ac.nz!virtue!canterbury.ac.nz!phys169
From: phys169@canterbury.ac.nz
Newsgroups: comp.os.msdos.programmer
Subject: Re: Communicating With Resident Programs (drivers)
Message-ID: <1990Oct2.144706.9279@canterbury.ac.nz>
Date: 2 Oct 90 06:33:42 GMT
References: <679@digigw.digital.co.jp>
Organization: University of Canterbury
Lines: 17

In article <679@digigw.digital.co.jp>, gday@digigw.digital.co.jp (Gordon Day) writes:
> Could somebody suggest the best way to communicate with a driver?  I have 
> successfully implemented a block device driver, but I am at a loss as to the
> best way to communicate with it from a transient program. 

The "correct" method, from DOS 2 onwards, is probably to use the IO Control
facility, i.e. set the IOCTL bit in the attribute word of the header (bit 14),
and provide a method of reading and writing bytes with command codes 3 & 12
(respectively) passed from DOS to the driver when you  use certain DOS function
0x44 calls. If you can't find it in the manual call me and I'll explain it a
little better, perhaps send you/post some code. 

Using "spare" interrupts around $60-$6F might clash with DECnet DOS software
(which uses a great number of them). Using interrupt 0x2f is a little better,
but the IOCTL method is best (though rarely used, goodness knows why).

Mark Aitchison, Physics computologist, University of Canterbury, New Zealand.