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7-1
BASIC BOARD MODULE (BBM)
SECTION 7 BASIC BOARD MODULE (BBM)
7.1 DESCRIPTION
The Basic Board Module (BBM) is the mother
board of the following modules:
• Dispatch Interface Module (DIM)
• Intelligent Dispatch Module (IDM)
• Dispatch Channel Module (DCM)
• Channel Interface Module (CIM)
• Telephone Interface Module (TIM)
• System Network Module (SNM)
• Conventional Channel Module (CCM)
• Logging Encoder Module (LEM)
• Voter Diagnostic Module (VDM)
• Multi-Net Console Module (MCM)
• Conventional Patch Module (CPM)
• Wide Area Module (WAM)
These modules are made up of the BBM plus the
appropriate software and personality cards as
required.
The BBM uses four wire audio to connect to the
external equipment. There is an additional connection
for secondary data transmission.
7.1.1 MAIN AUDIO
The main external audio connection is via RXA±,
P1, pins 31 and 32, and TXA±, P1, pins 63 and 64.
These connections go to P33. This allows the person-
ality cards to intercept the lines. When a 2-Wire
connection is required on a module, it enters the card
via the RXA± connection. The personality card then
intercepts the signal on P33, pins 2 and 4. The receive
and transmit buffers are connected to the personality
card via P33 also. Refer to the Basic Board Module
block diagram, Figure 7-1.
7.1.2 SECONDARY COMMUNICATION
There is a secondary communication connection
to the BBM. This is used to pass data information to
and from an external device, i.e. the Multi-Net Logic
Module (MLM), another SNM, etc. These connec-
tions are the RXS±, P1, pins 27 and 28, and TXS±, P1,
pins 59 and 60. There are two forms of communica-
tion on these lines, digital and audio frequency shift
keyed data. The form of communication is determined
by the switch setting of S3 and S4.
7.1.3 INTERNAL COMMUNICATION
There are several switch selections for the proper
internal routing and use of the audio. This occurs via
switch S1 and J27. There are several internal commu-
nication buses that are selected for operation of the
microprocessor. These include both data and audio
buses.