Re: A85: Weird Question
[Prev][Next][Index][Thread]
Re: A85: Weird Question
In a message dated 4/3/99 3:12:55 PM MST, DorkReMi@aol.com writes:
> Hey, guys, this is a typical Josh question, but is there any way grayscale
> could be done over the top half or so of the screen only?? I'm thinking
> grayscale is all about ldir's at different rates, so I'm hopin so. :) Just
> curious...
Yeah, a typical Josh question...
Grayscale is implemented using port...I think it's 1 or 0. What happens is
that at every few interrupts, the byte at that port is switched so the screen
displays another area of memory...it has nothing to do with ldir or anything
(that'd be *way* too slow). The only way you could make it *look* like
grayscale was at the top half was if you, for example, copied the bottom half
(or whatever you wanted to not be grayed) of the first page to the second.
I'm sure there's other ways, of course...but probably not the ways you hoped
for ;)
JL