Hardware Reference
In-Depth Information
which can be found on older systems.
PC and XT
The first popular PC motherboard was, of course, the original IBM PC released in August 1981.
Figure 4.1
shows how this board looked. IBM followed the PC with the XT motherboard in March
1983, which had the same size and shape as the PC board but had eight slots instead of five. Both the
IBM PC and XT motherboards were 9 inch ×13 inch. Also, the slots were spaced 0.8 inches apart in
the XT instead of 1 inch apart as in the PC (see
Figure 4.2
)
. The XT also eliminated the little-used
cassette port in the back, which was supposed to be used to save BASIC programs on cassette tape
instead of the much more expensive (at the time) floppy drive.
Figure 4.1. IBM PC motherboard (circa 1981).
