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From: nather@utastro.UUCP (Ed Nather)
Newsgroups: net.micro.pc
Subject: Re: Undocumented MS-DOS call for getting the switch char
Message-ID: <231@utastro.UUCP>
Date: Sat, 4-Jan-86 12:49:47 EST
Article-I.D.: utastro.231
Posted: Sat Jan  4 12:49:47 1986
Date-Received: Mon, 6-Jan-86 03:07:09 EST
References: <3340005@csd2.UUCP>
Organization: U. Texas, Astronomy, Austin, TX
Lines: 21

> There is an undocumented call to DOS which uses interrrupt 21h with (AH) =
> 37h. Upon return from this call (DL) will contain the ASCII value of the
> current switch character in it. 
> 
> NOTE: I have heard that changing the switch character does not work under
> MS-DOS 3.0+, so for many of you this may be less than useful.
> 
> 				Nicholas Jacobs

The call to function 37h can also be used to SET the switch character,
and it works the same in DOS 2.x and 3.x.  I have a huge assembly language
program (8 bytes long) that sets the switch character to "\" because
setting it to "-" means you can't have filenames like "pc-write," since
DOS then tries to find a file called "pc" and give it the switch "-w".
One can then use "/" to separate pathnames, as in Unix.

-- 
Ed Nather
Astronomy Dept, U of Texas @ Austin
{allegra,ihnp4}!{noao,ut-sally}!utastro!nather
nather@astro.UTEXAS.EDU