IBM 3745 Series, Hardware Maintenance Reference

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LIC Types 1 to 4 Cards
The LIC types 1 to 4 provide DTE function only. They connect the DMUX card to
various types of DCEs or direct-attached DTEs.
There are four types of LICs according to the CCITT interfaces.
LIC1s to LIC4s to DMUX interconnection is identical (the number and meaning of
bits may however differ according to the type of DCE attachment).
Some LICs require internally generated clock signals for either:
Ÿ Low-speed DCE attachment
Ÿ Direct attachment to terminals.
The internal clock function (ICF) on the LIC card itself, provides these clock facili-
ties.
Interface Lines
DMUX buses DTE to DCE interfaces
Power ON reset ┌────────────────────┐ Modem-out lines
────────────────5─┤ ├────────────────────5
LIC reset │ ├────────────────────5
────────────────5─┤ │ Modem-ln lines
│ ├─%───────────────────
│ ├─%───────────────────
ICF clocks (3) │ │
────────────────5─┤ │ Transmitted data
LIC clocks (3) │ ├────────────────────5
────────────────5─┤ │ Received data
Other clocks │ ├─%───────────────────
────────────────5─┤ LIC │
│ │ DCE receive clock
Super frame, │ ├─%────────────────────
Frame sync │ │ DCE transmit clock
────────────────5─┤ ├─%────────────────────
Frame inbound │ │ Transmit clock from ICF
%─────────────────┤ ├─────────────────────5
Frame outbound │ │
────────────────5─┤ │
│ │ Cable ID
│ ├─%────────────────────
│ ├─%────────────────────
└────────────────────┘
Chapter 4. Transmission Subsystem (TSS)
4-43