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Principles of Operation
Introduction
3
This chapter has a description of the HP 30240A ThinLAN 3000
IV
Link, Local
Area Network Interface Controller (LANIC). The description gives the
principles of operation.
Functional Description
The HP 30240A ThinLAN 3000/V link is an implementation of the IEEE
8022 and IEEE 802.3 Local Area Network (LAN) standards and is used to allow
HP 3000 computer systems to communicate with other HP 3000's over a Local
Area Network (LAN). The IEEE 8022 Local Area Network standard defines a
logical link control protocol, and IEEE 802.3 Local Area Network standard
defines a bus utilizing CSMA/CD (Carrier Sense Multiple Access/Collision
Detect) as the access method.
The ThinLAN 3000/V link functions as an intelligent Direct Memory Access
(DMA) channel which communicates with the host system via the system
backplane. Local intelligent control is provided by a microprocessor and
firmware on the LAN Interface Controller (LANIC).
The ThinLAN 3000/V link consists of a LAN Interface Controller (LANIC), an
Attachment Unit Interface (AUI), and a Medium Attachment Unit (MAU). The
MAU attaches to a coaxial cable which connects the various computer systems
together on the Local Area
Network~
and the LANIC provides the interface
between the LAN and the computer system.
LAN Interface Controller (LANIC)
The LANIC is an intelligent DMA channel which communicates with the host
system via the system backplane. On the network end of the LANIC. the AUI
carries bit-serial data and control information to and from the MAU. which
attaches directly to the network coaxial cable. A functional block diagram of
the LANIC is shown in Figure 3-1.
Principles of Operation
3-1
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