Hardware Reference
In-Depth Information
1980s for early PCs included CGA, EGA, MDA, and HCG. These were all digital inter-
faces.
Note
For more information on these early display standards, see
Upgrading and Repairing PCs,
10
th
Anniversary edition,
now out of print but may be available at some bookstores or librar-
ies.
Unlike earlier digital video standards, VGA is an analog system. VGA came out in 1987
and began a shift from digital to analog that lasted for more than 20 years. Only recently
has there been a shift back to digital. Why go from digital to analog and then back to di-
gital? The simple answer is that analog was the least expensive way at the time to design
a CRT-based system that supported a reasonable resolution with a reasonable number of
colors. Now that technology has advanced and LCD panels have largely replaced CRTs,
going back to digital interfaces makes sense.
The video interfaces (and connectors) you are likely to encounter in PCs dating from the
late 1980s to the present include the following:
•
VGA
•
DVI
•
HDMI
VGA is an analog connection, whereas the others are digital. The connectors for these in-
terfaces are shown in
Figure 12.2
and are discussed in further detail in the following sec-
tions.
Figure 12.2
Video interface connectors used in PCs from the late 1980s to the present.
