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Servicing Personal Computers, 3rd Edition
book

Servicing Personal Computers, 3rd Edition

by Michael Tooley
May 2014
Intermediate to advanced content levelIntermediate to advanced
320 pages
13h 41m
English
Newnes
Content preview from Servicing Personal Computers, 3rd Edition
58 Servicing Personal Computers
Figure 1.64. RS-232 ports (COMI and COM2) in an IBM PC/XT compatible (note the line drivers and
line receivers, U3 to U6)
The voltage levels in an RS-232C system are markedly different from those within the
computer. In the transmit and receive data paths, for example, a positive voltage of between
3 V and 25 V is used to represent logic 0 while a negative voltage of similar magnitude is used
to represent logic 1. In the control signal paths, however, conventional positive logic is
employed;
a high voltage in the range 3 V to 25 V indicates the active or 'on' state while a
negative voltage of similar magnitud ...
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Publisher Resources

ISBN: 9781483193670