Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!apple!bionet!agate!saturn!ucscb.UCSC.EDU!lupin3
From: lupin3@ucscb.UCSC.EDU (-=/ Larry Hastings /=-)
Newsgroups: comp.sys.ibm.pc
Subject: Re: switchar in PC DOS 3.2
Message-ID: <5144@saturn.ucsc.edu>
Date: 16 Oct 88 10:28:20 GMT
References: <4501@polya.Stanford.EDU>
Sender: usenet@saturn.ucsc.edu
Reply-To: lupin3@ucscb.UCSC.EDU (-=/ Larry Hastings /=-)
Organization: MetaWare, Incorporated
Lines: 47

+-In article <4501@polya.Stanford.EDU>, lma@polya.Stanford.EDU (Larry M. Augustin) wrote:-
+----------
|
|   55/27H--Character Operations
|   (Change Incompatible Configuration)
|   
|   Entry:	AL	= 0	Return DL = ASCII switch character
|   	AL	= 1	Set switch character to DL
|   	AL	= 2	Return DL = availability byte
|   	AL	= 3	Set availability byte to DL
|   
|   Exit:	DL	= Value if AL = 1 or 3
|   
| What is 55/27H?  It's not interrupt 27H, that's TSR.  The poster might
| have meant DOS functional call 55H, which is "used internally by DOS."
| I tried that, but it crashed my machine.  DOS function call 27H is a
| random block read.  Can someone explain?
+----------

  Um, that's wrong.  Here's the body of a short ASM program I run every day.

		mov ax,3701h
		; ah = 37 (switchar request code); al = 1 (set)

		mov dl,2dh
		; 2d sets switchar to - and dir sep to /;

		; change 2d to 2f to set switchar back to /
		; and dir sep to \

		int 021h

  Like I said, I use it every day.  Whoever typed in the example from the Zenith
manual got the function wrong... it's (obviously) int 21h, function 37.
  I'd like to point out that this doesn't work all that well with DesqVIEW.
Whenever you open a new window after running this program (either from inside
DV or outside) the new window won't inherit any of your environment variables
(blank path, prompt is C>, etc.).  They said they may fix it.

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