American Megatrends MegaPlex II, System Manual

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Chapter 1 Hardware Installation 11
Step 2 Configure CPU Board,
Continued
J3 CPU Clock Ratio J3 is an 8-pin berg on the Series 769 motherboard that sets the CPU clock
ratio. The external clock speed is always 100 MHz. In the 769 motherboard
graphic on page 4, Pin 1 of J3 is marked by the chamfered corner.
J3 Ratio Internal CPU
Speed
Short Pins 1-2
Short Pins 7-8
5:1 500 MHz
Short Pins 1-2
Short Pins 3-4
Short Pins 7-8
4:1 400 MHz
This is the default
setting.
Short Pins 5-6
Short Pins 7-8
7:2 350 MHz
Short Pins 3-4
Short Pins 7-8
9:2 450 MHz
DRAM Speed Settings J8 (on the CPU board) and J2 (on the memory expansion card) select
DRAM speed.
J8/J2 DRAM Speed
OPEN (factory setting) 60ns EDO DRAM
Short 50ns EDO DRAM
Note: The DRAM speed setting should be the same on both the CPU card and
the memory expansion card.
Installing One or Multiple CPUs
Number of CPUs
to be Installed
CPU Installation
1 - 3 Install one to three CPUs in the CPU
sockets and install a Series 776 CPU
terminator card in the remaining CPU
slots.
4 Install CPUs in all four CPU sockets.
Cont’d