HP 271308 Technical Reference Manual page 7

GENERAL INFORMATION
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INTRODUCTION
This manual provides general information, installation, principles of operation, programming, main-
tenance' replaceable parts, and schematic diagrams for the Hewlett-'-Packard model 27130B
Eight-Channel Multiplexer (MUX). This chapter has general information about the MUX, and in-
cludes a description with specifications.
PHYSICAL DESCRIPTION
The HP 27 1 30B Eight -Channel Multiplexer (MUX) card is shown in Figure 2 -1. The MUX consists of
a printed circuit card, a cable, an RS- 2 32 -C connection panel, a cable extender kit and an installation
manual.
FUNCTIONAL DESCRIPTION
The HP 27130B 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 1-1 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 are 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 1-1)
controls the flow of traffic between the I/O channel a·nd the memory/processor bus.
The HP 27130B uses several of the Z-80A family of microprocessor components to relieve the host
computer of much of the overhead. This permits a wide range of configurable transmission modes and
formats, th us' allowing connections to various· CR Tterminals, printing'termina:ls,printer(-and piotters;
1-1