Download WINDOWS ASSEMBLY LANGUAGE & SYSTEMS PROGRAMMING

9
Direct Hardware
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Preamble
Wbaf 3
in this
chapter
This chapter contains practical code to “get behind the scenes”.
The first part of the chapter focuses on the issues of direct reading
from and writing to memory, particularly video-RAM, and the
second part focuses on I/O.
I have shown the use of DPMI NT-3 lh services and of the
TNT-2Fh extensions, plus the use of low-level Windows functions.
I have pointed out overlap between the two where it occurs.
You will be amazed to learn that it is possible to have an
application running in a window, yet the application can write
directly to the video hardware, at breathtaking speed, without all
of the Windows rigmarole. This is the kind of practical code
developed in this chapter.
You will also learn about I/O aspects, such as use of the IN and
OUT instructions.
Mostly I view the material of this chapter as educational. It pokes
around doing fun things that may be viewed as “hacking”. It may
be that you will never use some of the less orthodox material in
professional applications, but what will be formed now is a good
solid foundation of understanding of the fundamentals.
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