Philips SBX12, Operating Instructions Manual

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4. The spare mains fuse is located on this board.
5. The 12 way flat ribbon cable connects the display board to the Mother Board.
6. Alphanumeric Display. This 4 digit display allows monitoring of digits as
keys are being stored in the system short cable store. It is also
possible to display a number currently stored in a certain slot. Numbers more
than 4 digits long are displayed in 4 digit groups
Microprocessor Card
1.
This board has provision for two Eprom chips to be inserted i.e. One 16k chip
plus one 8K chip, 24k total.
2. This board has a single Nicad battery to back up random access memory (RAM).
This is to maintain customers programmed during mains fail (ie call divert).
3. CPU functions.
(a) The CPU maintains a data set which describes the complete system state.
(b)
CPU processing section interprets changes in the extension and exchange
by continuously monitoring the current detectors.
(c) It detects dial pulses or DTMF signals by also monitoring the link and
DTMF card.
(d) It then uses the signaled information to decide what reed relays or other
equipment must be operated to complete the call.
Exchange Line Interface Circuits, ELIC
The ELIC provides:
1. Line Loop circuit.
2. Line current monitoring.
3.
Dial tone detection.
4. Ring detection.
5. Dial pulsing for out dialing.