Specifications

Theory of Operation
152 025-9035AA
The clock signal is a 1.544 MHz square wave that synchronizes the serial data. Eight clock
pulses constitute a “slot”. Audio is converted into 8-bit words and presented in one slot.
Twenty-four slots constitute a “frame”. The sync pulse marks the beginning of a frame
and is one clock cycle of duration with a period of about 125 microseconds (8 kHz
sampling rate). Each slot can be thought of a channel carrying unidirectional audio
information (just like a radio channel).
The CPU card provides six slots, or channels, of tones available to any card on the
highway. This is the source of all of the telephone prompts and some of the station card
prompts.
The non-volatile RAM and real time clock function is provided by a special socket in
which U50 resides. The socket eliminates the need for a separate real-time clock board on
the IBM bus.
An RS-232C compatible input/output port provides direct connection between the office
computer and the Series 2000 terminal. This port operates at 1200/9600 baud.
The connector to the card is brought out on a cable ending in a female DB-25. The pinout
for this connector is shown in Table 18 (refer to the Local Connect portion of the
troubleshooting section for cabling details):
Table 18: RS-232 Connector Pinout
The approximate cable length, assuming good quality shielded twisted pair cabling,
should not exceed 60 feet.
There are a series of switches at the top of the CPU card. These are used to set various
hardware and software options. Some of the software options also apply to the older
Master card system.
Pin # Signal Name
2 Transmit Data
3 Receive Data
4Request to Send
5 Clear to Send
6 Data Set Ready
7 Ground
8 Carrier Detect
20 Data Terminal Ready