Ziatech Corporation ZT 8809A, Руководство по эксплуатации

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Introduction
Jumpers are provided to select whether the following three groups of
devices, either individually or as a whole, are to be battery-backed:
•
Real-time clock and 32 Kbyte RAM
•
Two RAM sockets
•
ROM/RAM socket when RAM is present
This conserves battery power exclusively for those devices that
require backup.
AC/DC Power-Fail Detection
DC power-fail detection senses when DC voltage drops below 4.75 V.
This signals the board to switch into battery backup mode, as
described above. AC power-fail detection is also available for early
warning of impending low DC voltage, to give the processor time to
store critical data while DC voltage is still above 4.75 V.
An optional 24 V transformer is available from Ziatech (ZT 90020) to
monitor the same AC source supplying the STD bus card cage, and
may be attached to the ZT 8809A via the frontplane. Upon detection
of AC voltage falling below 90 VAC, a non-maskable interrupt
(NMIRQ*) is sent to the CPU to prepare for the power down.
Approximately 2 ms after a DC power failure, the battery is switched
in and simultaneously the DCPWRDWN* STD bus signal (pin 6) is
driven active low.
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