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14 Series 90-70 Hot Standby CPU Redundancy User’s Guide – December 1993
GFK-0827
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PRIMARY UNIT SECONDARY UNIT
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Genius Bus
CPU 780
Redundancy Communications Link
Redundancy Communications Link
a47002
Figure 3. CPU 780 Locations in a Hot Standby CPU Redundancy System
The capacities for the CPU 780 are as listed in the following table.
Table 1. Capacities for Redundancy CPU, IC697CPU780
Speed
(MHz) Processor
Input
Points
Output
Points
On-Board
User Memory
Expansion Memory
(KBytes)
Floating Point
Math
16 80386DX 12288 12288 not available 128/256/512 Yes
The total number of Input points and Output points on the model 780 CPU cannot exceed 12288.
CPU Architecture
The CPU 780 has an 80386DX microprocessor as the main processing element, on-board
memory, a dedicated VLSI processor for performing boolean operations and interfaces
to a serial port and the system bus. The microprocessor provides all fundamental sweep
and operation control, plus execution of non-boolean functions. Boolean functions are
handled by a dedicated, VLSI, Boolean Coprocessor (BCP) designed by GE Fanuc.
Program and data memory on the CPU 780 is available by the attachment of an
expansion memory board with either 128 Kbytes, 256 Kbytes or 512 Kbytes of
battery-backed CMOS RAM, or 256 Kbytes with 256 Kbytes of non-volatile flash
memory.
When the CPU board is in storage, disconnect the lithium battery if there is no
application program stored in memory. If a program is stored in memory, do not
disconnect the battery; otherwise the data will be lost.
Caution
If a Low Batter y War ning occurs, replace the battery before removing
power from the rack. Otherwise there is the possibility that data will
be corrupted or the program will be cleared from memory.
Watchdog Timer
The CPU provides a watchdog timer to catch certain failure conditions. The value of this
timer is controlled by the user from the programmer. The valid range of the watchdog