On (28 May 97) Barry Block wrote to Jerry Coffin...
 BB> Hello Jerry,
 JA>> ...put the screen in 80x50 text mode...
 JC>         mov ax, 1202h   ; int 10h, function 12h, subfunction 30
 JC>                         ; sets the
 JC>         mov bl, 30h     ;   number of scan lines.  AL: 0=200,
 JC>         int 10h         ;   1=350, 2=400 scan lines.
 JC>         mov ax, 3       ; AFTER setting the number of scan lines,
 JC>         int 10h         ;   set mode 3
 JC>         mov ax, 1112h   ; Now select the 8x8 ROM font and
 JC>         xor bx, bx      ;   reprogram the controller to use it.
 JC>         int 10h
 BB>      Perhaps,
 BB>          mov ax,3
 BB>          int 10h
 BB>      is to be considered.
That's exactly the code the original poster had that does _not_ work!
It will NOT change the number of lines on the screen.
 BB>      It is not needed if you are in mode3 already and will clear the
 BB> screen.
And worse yet, it won't leave you with 50 lines unless you were already
using 50 lines...
 BB>      This may not be desired.
 BB>      If the screen is in 132 column mode it will reset it to 80.
That's true.  Unless you 1) know the exact model of card in use, or 2)
at least know that the card supports VESA extensions, you can't do much
with 132 column modes.
 BB>      Maybe testing to see if in mode3 first is a good idea.
I don't think it's too useful.  You really have three choices: 1) stick
to VGA modes, in which case you ignore the possibility of 132 columns at
all.  2) Use VESA modes, in which case you simply change `3' to the
appropriate number (I don't have all the VESA numbers memorized...) or
3) write to a specific card and/or simply allow the user to enter a mode
number of their choice.
I was assuming the first option, sticking to VGA modes.
    Later,
    Jerry.
... The Universe is a figment of its own imagination.
--- PPoint 1.90
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