Specifications

Overview
149
Theory of Operation
Overview
This section presents the theory of operation for the paging terminal. Circuit descriptions
are provided for each of the cards. This section also contains a complete set of charts that
describe the sequence of events that takes place when call are processed by the paging
terminal (call processing charts). A complete set to timing diagrams for the telco side of
the system and the radio side of the system is contained at the back of the section.
The Series 2000 Paging Terminals are multiple microprocessor systems whose software
intensive architecture greatly reduces the cost of dial-access paging compared to older
technologies. A central processing unit (CPU 702-9176) controls all internal operations in
accordance with a paging control program stored on hard disk. The CPU provides system
power down detection, system reset, software “watchdog”, system clock calendar, timing
for the PCM highway, progress tones, temperature, and system status lights. A 1200/9600
baud Modem Card (802-0041) connects to the office computer for database management
and remote maintenance. With the local connection, the CPU also provides an RS-232
interface for direct connection of the office computer without requiring a dial-up
telephone line for subscriber management. The Hard disk Card (950-9618 or 950-0258)
contains disk storage to hold the paging software, trunk/station/voice card firmware,
subscriber database, system log files, and voice files to operate the Series 2000 terminals.
System Startup
After an input power cycle or a remote ZlinkW “reboot” command, the CPU card resets
all cards in the system. Each card in the system blinks its lights for a few seconds to
indicate it is alive. The CPU card then performs a test on the system memory (about 30
seconds) during which time most of the system lights are static.
The CPU then loads the Disk Operating Software (DOS) from the boot portion of the hard
disk. DOS in turn accesses the file named “
autoexec.bat” which does some