Path: utzoo!attcan!uunet!zephyr.ens.tek.com!tekcrl!tekgvs!toma
From: toma@tekgvs.LABS.TEK.COM (Tom Almy)
Newsgroups: comp.sys.ibm.pc
Subject: Re: i/o routines and non-standard v
Message-ID: <6406@tekgvs.LABS.TEK.COM>
Date: 21 Nov 89 18:29:56 GMT
References: <130954@<89320> <110200032@uxe.cso.uiuc.edu>
Reply-To: toma@tekgvs.LABS.TEK.COM (Tom Almy)
Organization: Tektronix, Inc., Beaverton,  OR.
Lines: 25

In article <110200032@uxe.cso.uiuc.edu> mcdonald@uxe.cso.uiuc.edu writes:
>
>>The problem is that while Turbo's own screen package will take advantage of
>>whatever size screen you are using, DOS (not necessarily BIOS) is hard-coded
>>to work with only the first 25 lines of the screen.  The problem here is that
>>to do anything else, DOS would have to automagically sense the current screen
>>size [...]

[sample program that puts VGA display in 50 line mode]

>does DOS then use 50 lines? If I do a "dir" I get 50 lines. IF I
>do a print screen, it prints all 50 lines. [...]

DOS handles the extra screen size just fine since it has the BIOS do it.
On the other hand ANSI.SYS, which comes with DOS, prior to DOS 4.0 would
not handle these extended modes. I'm not sure (haven't tested) if ANSI.SYS
will handle 132 column modes even with DOS 4.0.

"Automagically sensing screen size" is real easy since the number of
columns is in a known RAM location, and the number of rows for all but
CGA and Monochrome is in another known RAM location.

Tom Almy
toma@tekgvs.labs.tek.com
Standard Disclaimers Apply