Specifications

CHAPTER 10
CONFlGURATtON AND INSTALLAflON PLANNING
MODULAR CONSTRUCTlbN
Physically, the PDP.11 is composed of a number of System Units. Each
System Unit is composed of three 8-slot connector blocks mounted end-to-
end as shown in Figure 10-l. The Unibus connects to the System Unit at
the lower left and at the upper left. Power also connects to the unit in the
leftmost black. A System Unit is connected to other System Units only via
the Unibus.
UNIBUS CONNECTION
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Figure 10.1 System Unit
The remainder of the System Unit contams logic for the processor, memory
or an I/O device interface. This logic is composed of single height, double
height, or quad height modules which are 8.5 ” deep.
The use of System Units allows the PDP-11 to be optimally packaged for
each individual application. Up to six System Units can be mounted into a
single mounting box. For a basic PDP-ll/PO system, the processor/console
would fill 21/2 System Unit spaces and 4096 words of core memory would
fill one System Unit space. This leaves 21/, spaces for user-designated op
tions. This would allow the user to add 8,192 words of additional core
memory, a Teletype control, and a High-Speed Paper Tape Control, or 4,096
words of core memory and six Teletype interfaces, Larger systems will
require a BAll-EC or BAll-ES Extension Mounting Box which contains space
for six additional System Units.
The use of System Units also facilitates expansion of systems in the field
and service. To add an additional option to a PDP-11 system, the proper
System Unit is mounted in the Basic or Extension Mounting 80x and the
Unibus is extended. Servicing of the PDP-11 can be done by swapping
modules or by swapping System Units.
MOUNTING BOXES AND CABINETS
The PDP-11 is available as either a tabletop or rack-mounted configura-
tion. The rack-mounted configuration may be installed in a DEC cabinet or
mounted in a customer cabinet. The PDP-11 mounts in an EIA standard 19-
inch cabinet. The rack-mounted PDP-11 has tilt-slides as standard mount-
ing hardware.
1 The following mounting units and cabinets are‘available for PDP-II systems.
PDP-11 TABLETOP BOX AND POWER SUPPLY FOR 11/20, ll/lO SYSTEMS-
fBAll-CC AND H720)-This cover and box may be specified with a basic
i1/20 and ll/lO system and includes:
'1. H720 Power Supply
2. 15’ of power cord with ground wire
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