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GENERAL INFORMA TION
Irl~II.II'
This manual provides general information, installation, theory of operation,
maintenance
instruc-
tions,
replaceable
parts
information,
and
servIcIng
diagrams
for
the
Hewlett-Packard
HP 27130A Eight-Channel Multiplexer (MUX). This chapter contains general information concern-
ing the MUX, and includes a description and specifications.
PHYSICAL DESCRIPTION
The HP 27130A Eight-Channel Multiplexer (MUX) is shown in fIgure 1-1 and consists of a printed
circuit card, a cable, an RS-232-C connection box, and an installation manual.
FUNCTIONAL DESCRIPTION
The HP 27130A
Eight-Channel
Multiplexer
provides
multiplexed
connections
between
a
Hewlett-Packard computer system and up to eight EIA RS-232-C/RS-423-A/RS-422-A type
devices (not including modems).
Figure 1- 2 shows a Hewlett-Packard computer system using CHANNEL I/O and the MUX.
(CHANNEL I/O is a Hewlett-Packard standard defining the physical and electrical characteristics
for an I/O system consisting of an I/O channel, an I/O channel adapter, and I/O cards. The MUX is
one of the I/O cards.)
Note that the computer system CPU and memory communicate directly along a Memory/Processor
Bus (MPB). I/O data to/from peripheral devices reaches the CPU/memory through the I/O channel,
the I/O channel adapter, and an I/O card such as the MUX card. The I/O data is received from
and transmitted to peripheral devices by the I/O card, which converts device-specific data to a
format compatible with the I/O channel, and thus the computer.
The I/O channel adapter (see
figure 1-2) controls the flow of traffic between the I/O channel and the memory/processor bus.
1-1
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