Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!zaphod.mps.ohio-state.edu!caen!uflorida!gatech!mcnc!rti!bbt!djb
From: djb@bbt.UUCP (beauvais)
Newsgroups: comp.sys.ibm.pc.misc
Subject: Re: screen clearing program
Message-ID: <1038@bbt.UUCP>
Date: 3 Dec 90 14:01:11 GMT
References: <684.273AC585@gisatl.FIDONET.ORG>
Reply-To: djb@bbt.UUCP (beauvais)
Organization: Broadband Technologies, Inc., Research Triangle Park, NC
Lines: 47

In article <684.273AC585@gisatl.FIDONET.ORG> david.deitch@gisatl.FIDONET.ORG (David Deitch) writes:
>Anyone have a program for EGA/VGA systems that will clear the number of lines 
>on the screen, ie 43 lines, 50 or 60 lines?  CLS only clears the top 25.


It's pretty easy to write your own...  Pick you favorite programming
language.  Read the video mode, and write the mode back.  Any time you
write the video mode, the screen clears.  You can read the current video
mode by executing INT 10(hex) service 0F(hex).  You can set the video mode
by executing INT 10 service 0.  In both cases, the the service # goes in
the AH register, the mode is in the AL register.

Here's an assembly language example:

	mov	ah,0fh	;service 0F, get video mode
	int	10h	;video interrupt
	mov	ah,0	;service 0, set video mode
	int	10h	;video interrupt

You can hack this with DEBUG.


Or, if you prefer Turbo C:

#include <dos.h>

#define VIDEO 0x10
#define		GET_MODE	0xf
#define		SET_MODE	0


void clearscreen()
	{
	union REGS regs;

	regs.h.ah = GET_MODE;
	int86 ( VIDEO, &regs, &regs );

	regs.h.ah = SET_MODE;
	int86 ( VIDEO, &regs, &regs );
	}

-- 
Dan Beauvais                        UUCP:      ...!mcnc!rti!bbt!djb
BroadBand Technologies, Inc.        Internet:  djb%bbt@rti.rti.org
Box 13737                           BITNET:    djb%bbt%rti.rti.org@CUNYVM
Research Triangle Park, NC  27709   +1 (919)-544-6850 ext. 295