Misc/abrash-black-book
Watch
1
0
Fork
You've already forked abrash-black-book
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Normal quotes

Browse source
This commit is contained in:
James Gregory 2013-12-30 18:34:31 +11:00
commit 18011c595a
352 changed files with 6040 additions and 6040 deletions
Download patch file Download diff file Expand all files Collapse all files

16
45-05.md
View file

@ -80,7 +80,7 @@ flipping.
int i;
for (i=0; i<30; i++) {
/* Wait until we’re not in vertical sync, so we can catch leading edge */
/* Wait until we're not in vertical sync, so we can catch leading edge */
while ((inp(INPUT_STATUS_1) & 0x08) != 0) ;
/* Wait until we are in vertical sync */
while ((inp(INPUT_STATUS_1) & 0x08) == 0) ;
@ -89,22 +89,22 @@ flipping.
After I described 640x400 mode in a magazine article, Bill Lindley, of
Mesa, Arizona, wrote me to suggest that when programming the VGA to a
nonstandard mode of this sort, it’s a good idea to tell the BIOS about
nonstandard mode of this sort, it's a good idea to tell the BIOS about
the new screen size, for a couple of reasons. For one thing, pop-up
utilities often use the BIOS variables; Bill’s memory-resident screen
utilities often use the BIOS variables; Bill's memory-resident screen
printer, EGAD Screen Print, determines the number of scan lines to print
by multiplying the BIOS “number of text rows” variable times the
“character height” variable. For another, the BIOS itself may do a poor
by multiplying the BIOS "number of text rows" variable times the
"character height" variable. For another, the BIOS itself may do a poor
job of displaying text if not given proper information; the active text
area may not match the screen dimensions, or an inappropriate graphics
font may be used. (Of course, the BIOS isn’t going to be able to display
font may be used. (Of course, the BIOS isn't going to be able to display
text anyway in highly nonstandard modes such as Mode X, but it will do
fine in slightly nonstandard modes such as 640x400 16-color mode.) In
the case of the 640x400 16-color model described a little earlier, Bill
suggests that the code in Listing 45.4 be called immediately after
putting the VGA into that mode to tell the BIOS that we’re working with
putting the VGA into that mode to tell the BIOS that we're working with
25 rows of 16-pixel-high text. I think this is an excellent suggestion;
it can’t hurt, and may save you from getting aggravating tech support
it can't hurt, and may save you from getting aggravating tech support
calls down the road.
**LISTING 45.4 L45-4.C**