Xref: utzoo comp.sys.ibm.pc:28960 alt.msdos.programmer:49
Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!rutgers!ukma!uflorida!usfvax2!ateng!chip
From: chip@ateng.ateng.com (Chip Salzenberg)
Newsgroups: comp.sys.ibm.pc,alt.msdos.programmer
Subject: MS-DOS Redirectors:  How do they work?
Message-ID: <1989May17.191901.16666@ateng.ateng.com>
Date: 17 May 89 23:19:01 GMT
Organization: A T Engineering, Tampa, FL
Lines: 26

I've become interested in the use of "redirectors" in extending MS-DOS's
idea of a file system.  Essentially, there are two ways to make MS-DOS
network:

    A network SHELL intercepts interrupt 21H, notices requests for access to
    virtual drives, and performs the requested action without MS-DOS ever
    knowing what happened.

    A network REDIRECTOR intercepts an MS-DOS interrupt intended
    specifically for network extensions.  This interrupt is called at
    strategic points in the processing of file requests, and gives the
    network extension a chance to do its thing.

Now, I'm sure that given enough time (:-)) I could write a shell, but I'd
much rather write a redirector.  The only problem is that Microsoft doesn't
release info about how to do it!  Their reason becomes clear when you realize
that they license their for mucho bucks.

So:  Does anyone out there know where redirectors hook in?  Even a solid
lead on an interrupt number will gain my eternal gratitude.

(Well, I'll kiss your feet, anyway.)
-- 
Chip Salzenberg             <chip@ateng.com> or <uunet!ateng!chip>
A T Engineering             Me?  Speak for my company?  Surely you jest!
	  "It's no good.  They're tapping the lines."