Real Time Clock - Data General NOVA 4/C Field Engineering Maintenance Manual

Data General Corporation (DGC) has prepared this manual for use by DGC personnel and customers as a guide to the proper installation, operation, and
maintenance of DGC equipment and software. The drawings and specifications contained herein are the property of DGC and shall neither be reproduced in whole or
in part without DGC's prior written approval nor be implied to grant any license to make, use, or sell equipment manufactured in accordance herewith.
1 MAIN
q VIRTUAL
TO 1/0
A —-—- —A— ——
5 DEVICE
QQ )
Y
20 mA CURRENT LOOP OR
EIA RS-232 COMMUNICATIONS LINE
Figure 1.7 Simplified printed circuit board interconnection diagram
Main memory contains a dynamic RAM array and refresh
logic. Two different sizes of RAM arrays are available:
cycle time is 400 ns.
both a transmitter and receiver. It allows full-duplex
communications between a serial, asynchronous terminal
send/receive terminals, it supports both an automatic
paper tape reader) as well as a 60cps DASHER terminal
printer.
by the position of the front console Lock switch), a BREAK
character received by the interface interrupts the executing
Virtual Console
The virtual console allows a user whose terminal is
connected to the resident asynchronous interface to inspect
and modify the system's state and aid program debugging.
It provides the user with the ability to:
e Stop, start and continue program execution;
e Examine and/or alter CPU registers and memory
locations;
e Initiate program load sequences.
Real-Time Clock
This optional interface can supply program interrupt
requests at one of four program-selectable frequencies:
10Hz, 100Hz, 1000Hz or power line frequency.
For more information concerning the CPU board, see Part
III, Chapter 11.
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