Path: utzoo!attcan!uunet!crdgw1!sagittarius!dixon
From: dixon@sagittarius.crd.ge.com (walt dixon)
Newsgroups: comp.sys.ibm.pc.programmer
Subject: Re: How do file servers work?
Message-ID: <8435@crdgw1.crd.ge.com>
Date: 11 Jun 90 12:40:38 GMT
References: <30686@cup.portal.com>
Sender: news@crdgw1.crd.ge.com
Reply-To: dixon@sagittarius.crd.ge.com (walt dixon)
Organization: General Electric Corp. R&D, Schenectady, NY
Lines: 29

In <30686@cup.portal.com> Tim W Smith writes:

>How do file servers under DOS work?  That is, you've got these DOS
>programs that are issuing INT 21h requests for file access, and
>somehow these get translated into requests for files on a server.

>Do the people that implement file servers just intercept all INT 21h
>requests and process those that refer to the server, or is there a
>better way?

>How about things that are not file servers but have non-DOS file
>systems, such as ISO 9660 CD-ROMs?

>In general, what's the best way to make a non-DOS storage device
>work under DOS, assuming that the file system format for the device
>has already been defined and it is not a DOS file system, so you
>can't just implement a block device driver for it?

If one marks a logical drive as a network device,  DOS generates
int 2fh requests which can be mapped to another disk structure.
I'm not sure whether the format of these requests has been documented.
You might try looking on the interrupt list that Ralf Brown maintains.

Walt Dixon	{internet:	dixon@crd.ge.com	}
		{us mail:	ge crd			}
		{		po box 8		}
		{		schenectady, ny 12301	}
		{phone:		518-387-5798		}
Walt Dixon dixon@crd.ge.com