Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!lll-winken!brutus.cs.uiuc.edu!apple!ames!pacbell!att!dptg!pegasus!dmt
From: dmt@pegasus.ATT.COM (Dave Tutelman)
Newsgroups: comp.sys.ibm.pc
Subject: Re: MSDOS's recognition (?) of screen modes
Message-ID: <4365@pegasus.ATT.COM>
Date: 2 Jan 90 13:00:57 GMT
References: <4703@itivax.iti.org> <2593@jolnet.ORPK.IL.US>
Reply-To: dmt@pegasus.ATT.COM (Dave Tutelman)
Organization: AT&T Bell Labs - Lincroft, NJ
Lines: 59

Two otherwise correct responses to the base note propagate some
misinformation about the monochrome mode.

> From: leonard@bucket.UUCP (Leonard Erickson)
> Message-ID: <1869@bucket.UUCP>
>
> If you think waaaay back... to BASIC (anybody
> remember BASIC) it had to be able to print text in graphics modes. As
> I recall, the CGA modes are "hardwired to the 8x8 fonts and mode 7 is
> hardwired to 9x14. 

	Perhaps true, perhaps not, depending on what Leonard meant.
	True that:
	   -	Mode 7 is 9x14, and hardwired (REALLY, not BIOS).
	   -	BASIC was able to print text in graphics modes.
	Not true that:
	   -	BASIC printed its text in graphics modes in general.

	In fact, you had to explicitly call up a graphic screen mode;
	the default for basic was a text mode.  If you think waaaay
	back, the IBM mono adapter had NO graphic mode whatsoever,
	and (1) it was the basic IBM offering, and (2) BASIC was
	built into ROM on that IBM offering.

	Which brings us to...
 
> From: cox@jolnet.ORPK.IL.US (Ben Cox)
> Message-ID: <2593@jolnet.ORPK.IL.US>
> 
> If the BIOS doesn't know how to use a given
> mode, you will not see characters, and you may hang (although sometimes you
> can still type commands -- try typing "mode co80" sometime when you appear
> hung -- it may be just that you don't see anything, even though you are not
> hung -- you will reset to mode 3, which is 80x25 color text, or 7, which is
> BW 80x25).

	No, no, no.  The modes in confusion here are:
	   -	CO80: mode 3, color 80x25.
	   -	BW80: mode 2, b&w 80x25 _for_CGA-compatible_adapter.
	   -	MONO: mode 7, monochrome 80x25, for the mono adapter.

	Note that mode 7 is the ONLY mode supported by the basic mono
	adapter.  (Hercules came along later with their graphics mode.)
	Mode 2 is intended for use where you have a gray-scale monitor
	on a CGA card, and is the mode set by the command "MODE BW80".

	I suspect mode 7 will be the result if you say MODE CO80 to a
	computer with just a mono adapter in it.  It's also the mode
	if you say anything at all to such a computer.  I don't know
	for sure, but I very much doubt that it's the mode assumed
	by an adapter capable of CGA and mono emulation, in response
	to MODE CO80.

+---------------------------------------------------------------+
|    Dave Tutelman						|
|    Physical - AT&T Bell Labs  -  Lincroft, NJ			|
|    Logical -  ...att!pegasus!dmt				|
|    Audible -  (201) 576 2194					|
+---------------------------------------------------------------+