Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!crdgw1!uunet!cos!fetter
From: fetter@cos.com (Bob Fetter)
Newsgroups: comp.os.msdos.misc
Subject: Re: EGA and other text screens
Keywords: EGA,text screen height
Message-ID: <44421@cos.com>
Date: 29 Mar 91 14:05:15 GMT
References: <8196@dnlunx.pttrnl.nl>
Reply-To: fetter@cos.UUCP (Bob Fetter)
Organization: Corporation for Open Systems, McLean, VA
Lines: 43

In article <8196@dnlunx.pttrnl.nl> dondorp@dnlunx.pttrnl.nl (Dondorp E.) writes:
>first thank you for the 43 line EGA emulation. it't great.
>
>I did write several full screen programs for the PC range of computers.
>All these programs use a fixed 80x25 screen.
>But now that I have this EGA emulation and since I will soon
>be the proud owner of a VGA I have several questions:
>
>How can a program determine the width and height of the text screen.
>I found out there was a BIOS call that returned the number of
>character columns, but none returns the number of lines.
>I tried to figure out the height via the 'get screen mode' BIOS call
>only to find out that both 80x25 and 80x43 are screen mode nr 7.
>
>So the real question is: can I find out the screen height unambigously?
>	(and of course how?)
>
>Thanks
>	Erwin


  At *byte* location [0040:0084] in the BIOS data segment is the number
of EGA/MCGA/VGA rows on screen minus one.  Right after that, at :0085, is
one word containing the character height in scan-lines.

  In C, you can get this using (my code, probably laborious style, but
workable):

  static unsigned char far * bios_rows
		= (unsigned char far *)MK_FP(0x0040,0x0084);
  static int far * bios_cheight
		= (unsigned int far *)MK_FP(0x0040,0x0085);

  printf("Number of rows %d, char height %d\n",
		(int)(*bios_rows)+1,*bios_cheight);


  This and other goodies are in Ralf Brown's Interrupt List at SIMTEL20
at PD1:<MSDOS.INFO>INTER490.ZIP

  Hope this helps.

  -Bob-