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System Components
2.1.1 Port Card
The Port card includes the telephone line interface and the CODEC facility.
The telephone line interface transmits and receives analog and digital signals* to
and from the telephone line. The analog input signal is digitized at a sampling rate
of 8kHz to create an 8-bit digital signal.
The CODEC facility consists of two digital signal processors (DSP). When a user
calls the VPS, one of the DSPs compresses the digital signal sent from the tele-
phone line interface.
This compressed signal is stored on the hard disk as data.
When messages stored on the hard disk are played back, the DSP decompresses the
stored data and the resulting signal is then sent to the telephone line interface
where it is converted back to an analog signal.
* When used with KX-TD D-PITS Extension
2.1.2 CPU Card
The CPU card includes the central microprocessor, ROM, dynamic RAM, system
controller, a Rotary switch and a RS-232C interface., It is mounted inside the main
cabinet.
The central microprocessor communicates with and controls the DSPs on the Port
card via FIFO memory.
The system ROM stores ROM-based system programs, self-diagnostic software,
test programs and application program loader.
Application programs and the system administration table from the hard disk are
read into dynamic RAMS for use by the system.
The rotary switch has several functions:
-
Position 0: Normal setting
- Position 1: RS-232C parameters are initialized when the system is booted up.
This setting should be used if there is some uncertainty about the
parameters to be used when making connections.
Installation 2-5