Connector And Pin Identification; Component Description; Dpp Central Processor Unit - Nortel DMS-100 Series Product Manual

2-10 DPP Hardware
Connector and pin identification
J Connectors: These connectors, located on certain subassemblies, are
identified by the letter J, followed by up to three digits. For example, both the
A and B chassis have J connectors on the pin side of the backplane; numbers
increasing from right to left. AJ2 is located on the backplane of the A chassis.
J numbered connectors are also located on certain Printed Circuit Assemblies
(PCAs) and are described by first identifying the chassis number, the number
of the PCA, and finally the number of the connector. For example, B13 J1 is
located in the B chassis on the assembly occupying the 13th slot from the left,
viewing the chassis from the front. J numbers on PCAs are clearly marked.
J numbered connectors are located on certain assemblies, such as the disk
drives. Locations of these J connectors are illustrated in the Figures of the
specific subassembly.
Pin Number Identification: Pin numbers of a given connector are identified
by up to three digits following the designation of the connector. For example,
A13 J1 P34 designates the 34th pin of the connector located thirteen slots
from the left in the card rack of the A chassis, viewed from the front.
In many cases, locating a pin requires first locating the position of Pin 1.
Manufacturers use a variety of means to locate Pin 1; a dot (.), a printed
number 1, or a triangle are most common. Ribbon cables with multi-colored
conductors use a brown wire on the cable and a triangle on the connector to
indicate Pin 1. Many connectors have even-numbered pins on one side, odd-
numbered pins on the other. Some connectors, such as the DB-25 types used
in the DPP, number pins consecutively left to right, top to bottom, returning to
the left of the next row when the end of the upper row has been reached.

Component description

A typical DPP, showing the physical arrangement of the assemblies in the
cabinet, is shown in Figure 2-6.

DPP central processor unit

Both Central Processor Units (CPUs) can control the DPP and are
electronically linked to allow either processor to assume control should the
other fail. A disk crossover capability is also provided so that either CPU can
communicate with either disk drive. This crossover capability safeguards
against the loss of data if there is a malfunction in either processor. If the
system were to malfunction, the standby processor automatically takes
control.
297-1001-019 Standard 02.01 April 1997