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Path: utzoo!mnetor!uunet!husc6!mit-eddie!ll-xn!ames!ptsfa!ihnp4!ihlpe!psfales
From: psfales@ihlpe.ATT.COM (Pete Fales)
Newsgroups: comp.sys.ibm.pc,comp.sys.att
Subject: Re: Anyone know how to discover the DOS switch character?
Message-ID: <2260@ihlpe.ATT.COM>
Date: Thu, 5-Nov-87 21:54:57 EST
Article-I.D.: ihlpe.2260
Posted: Thu Nov  5 21:54:57 1987
Date-Received: Tue, 10-Nov-87 04:21:01 EST
References: <2678@ihlpf.ATT.COM>
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 25
Keywords: DOS, IBMPC, PC6300, switch, assembler
Xref: mnetor comp.sys.ibm.pc:9889 comp.sys.att:1692

In article <2678@ihlpf.ATT.COM>, warren@ihlpf.ATT.COM (Montgomery) writes:
> I have tried without much success to find a way of discovering from
> a program what the current DOS switch character is.  I am working
> with a C compiler and assembler that have no MS-DOS library support
> other than what I've written for them, so knowing I can call a
> library function in someone's support library doesn't help.  I need
> to know at the assembly language level how to dig up the
> information.

INT 21H, Function 37H can be used to to this.  This is not supported
officially by Microsoft, but apparently is fairly widely used.  The
information has appeared on Usenet in several forms, including programs
to read and set the switch character.  The following is excerpted from
a list of undocumented DOS functions that was posted a while back:

37   Get/set option marking character (i.e. usually "/").  AL=0
     to return character in DL, 1 to set from DL. In DOS 2, also can get/set
     forced-/DEV flag (if set, /DEV/ must preceed device names; otherwise
     it is optional): AL=2 to return flag in DL, AL=3 to set from DL (0 = set,
     1 = not set).
-- 
Peter Fales		UUCP:	...ihnp4!ihlpe!psfales
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