_G_E_N_E_R_A_L_In_F_O_R_Ma_T_I_O_N; Introduction; General Description - HP 30240A Installation And Service Manual

_G_E_N_E_R_A_L_IN_F_O_R_MA_T_I_O_N
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INTRODUCTION
This manual presents installation and service instructions for the HP 30240A OfficeShare LAN/3000
Link Local Area Network Interface Controller. This section has general information about the HP
30240A OfficeShare LAN/3000 link product, and includes a description and ·specifications.
GENERAL DESCRIPTION
The HP 30240A OfficeShare LAN/3000 link is an implementation of the IEEE 802.2 and IEEE 802.3
Local Area Network (LAN) standards and is used in HP 3000 computer systems. The HP 30240A allows
the HP 3000 to communicate with other HP 3000's over an IEEE 802.3, O. 18-inch baseband Local Area
Network (LAN).
The IEEE 802.3 Local Area Networks (LAN's) consist of three major elements: a coaxial cable
transmission medium, units to access this medium (Thin Medium Attachment Units, or Thin MAU's), and
controllers. For the HP 30240A, the controller is the Local Area Network Interface Controller (LANIC).
The HP 30240A OfficeShare LAN/3000 link is available for use with the HP 3000 Series 39, 40, and
42; and the HP 3000 Series 44, 48 64, and 68. The LANIC and Thin MAU, are the same for
an
HP 3000
Series; however, two different LANIC cables are offered (see the paragraph "Equipment Supplied").
The LAN/3000 link functions as an intelligent Direct Memory Access (DMA) channel which
communicates with the host system via the system I/O backplane. Local intelligent control is provided by
a microprocessor and firmware on the LAN Interface Controller (LANIC). An 8-bit Z-80B
microprocessor (MPU) on the LANIC handles all the LAN/3000-to-host communication and performs
many link-level operations independently of the host. A type 82586 Local Communications Controller
(LCC) on the LANIC performs high -speed serial operations, packet address checking, network contention
control, packet formatting, and Cyclic Redundancy Check (CRe) generation and checking. The LCC is
controlled by the Z-80B through local (card -resident) memory.
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