Chapter 1. System Overview and Modes of Operation
27
Microprocessor
The 32-bit Reduced Instruction Set Computer (RISC) microprocessor controls all functions
on the AMCU sub-board. The microprocessor executes the protocol stack, and handles
communication with the Ethernet 10Base-T and serial interfaces.
Flash EPROM
The FLASH EPROM is 1 M x 16.
DRAM
The DRAM is 1 M x 16.
EEPROM
The EEPROM is 256 x 16. It provides nonvolatile storage of AMCU card information,
such as card type, card serial number, Media Access Control (MAC) address, and
hardware revision and date. EEPROM data is entered during the factory test procedure,
and is read only during normal AMCU operation.
LEDs
The front panel of the AMCU has four Light Emitting Diode (LED) indicators. Two of the
LEDs glow green. One, marked ACO, indicates alarm cutoff, while the other green LED,
marked BYP, indicates that the multiplexer is being bypassed.
Another LED glows red to indicate a major alarm condition impacting service. It is marked
MAJ (major). The LED marked MIN (minor), which glows yellow, indicates faults
occurring that do not impact service. For more information on LEDs, see Chapter 3.
Installation, and Chapter 5. Diagnostics.
I/O Ports
The AMCU utilizes the standard CCU provisioning bus port and a COM port for “normal”
operation. The provisioning bus is an RS-485 half-duplex asynchronous port, while the
COM port is a full-duplex asynchronous RS-232C port with user-selectable data rates.
(Refer to Chapter 3. Installation, for details.)
An Ethernet 10Base-T port allows terminal emulation over a LAN for SNMP and Telnet
network management.
Code Download
Code download by the AMCU can be initiated in one of three ways:
1. Automatically on system start-up
2. External indication (pressing the ACO and BYP buttons at system power-up, and
holding for one minute)
3. Software menu selection
Code download occurs at system start-up after the AMCU computes the checksum of its
stored code. If a bad checksum is detected, the AMCU requests a code download from
the sub-board.
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