AT&T 3B2/300 Technical Reference Manual page 127

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ED-4C637-30 System Board
ED-4C637-30 System Board Layout
Figure 2-24 shows the layout of the component side of a typical System Board, ED-4C637-30. The
system board is a multilayer board measuring 7.7 inches wide by 14.8 inches deep. Refer to
Appendix B for connector pinout information. All system board interfaces are connectorized as follows:
• CONSOLE and CONTTY RS-232C Ports (JOI)
• Backplane Board (J02 and J03)
• Power (J04)
• Random Access Memory (RAM) Cards (MO/JOS and Ml/J06)
• Integral Hard Disk Control Bus (J07)
• Integral Hard Disk Data Bus O (J08)
• Integral Hard Disk Data Bus 1 (J09)
• Integral Floppy Disk Data and Control Bus (JlO)
• Nonvolatile Random Access Memory (NVRAM) Power (Jll)
• Diagnostic and Power Indicators (J12 and J13)
• Auxiliary Disk Interface Soft Power (J14).
The following major components on the system board are connectorized:
• Read Only Memory (ROM) (four Dual Inline Packages)
• WE 32100 Microprocessor Central Processor Unit (CPU)
• WE 32101 Memory Management Unit (MMU)
• 8.2/10-MHz Oscillator
• WE 32106 Math Acceleration Unit (MAU) (optional).
ED-4C637-30 System Board Versions (Series Information)
Different versions (groups) are used for the various 3B2 computer models. The differences among
the groups are the system clock (8.2 MHz or 10 MHz) and equipage of the WE 32101 MAU. The
system board groups are identified in the following table by the model of computer, system clock rate,
and MAU equipage. Not identified in the table is ED-4C637-30,G6 that is a stripped board (no ROM or
MAU) used for system board sparing.
SYSTEM BOARD
COMPUTER MODEL SYSTEM CLOCK MAU
ED-4C637-30,Gl
382/300 8.2 MHz -
ED-4C637-30,G2
382/400 10 MHz
NO
ED-4C637-30,G3 382/310 10 MHz NO
ED-4C637-30,G4
382/310 10 MHz
YES
ED-4C637-30,GS
382/400 10 MHz YES
EQUIPMENT DESCRIPTION 2-103