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From: mcdonald@uxe.cso.uiuc.edu
Newsgroups: comp.sys.ibm.pc
Subject: Re: i/o routines and non-standard v
Message-ID: <110200032@uxe.cso.uiuc.edu>
Date: 18 Nov 89 01:38:50 GMT
Article-I.D.: uxe.110200032
References: <130954@<89320>
Lines: 44
Nf-ID: #R:<89320:130954:uxe.cso.uiuc.edu:110200032:000:1352
Nf-From: uxe.cso.uiuc.edu!mcdonald    Nov 17 09:07:00 1989


>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, which, since it uses BIOS calls, would tremendously slow down screen
>I/O.  OS/2 can solve this problem easily, because it *always* knows what size
>the screen is.

Why then, pray tell, if I execute the following program:


cseg	segment para public 'code'
	org	100h
SETMOD	proc far
	assume cs:cseg,ds:cseg	
        mov     ax,3
        int     16
        mov     ah, 17
        mov     al, 18
        mov     bl, 0
        int     16
        mov     ah, 18
        mov     al, 0
        mov     bl, 32
        int     16
        mov     ah, 1
        mov     cx, 0407h
        int     16
	int	020h
SETMOD	endp
cseg	ends
end	SETMOD

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. If I execute WordPerfect 
v5 it uses 50 lines. IF I use a broken program that expects 25
lines only, when I get out of it, DOS gets back to work in 50 lines
properly?

This is DOS 3.3 on a Model 80 or a Dell 310.

Are you perhaps saying that command.com does not use DOS calls?
Doug McDonald