Digital Section; A20 Digital Motherboard (For Serial Prefix Jp1Kh, Jp2Kh, And My432); A20 Digital Motherboard (For Serial Prefix My433 And Later); A21 Analog Interface Board - Agilent Technologies E4991A Service Manual

Theory of Operation

Digital Section

Digital Section
A20 Digital Motherboard (for serial prefix JP1KH, JP2KH, and
MY432)
A20 digital motherboard provides basic system control and interface functions for the
instrument. It contains a CPU, ROM for BIOS, 128MBytes RAM, USB interface,
keyboard and mouse interfaces, and interfaces to PCI (Peripheral Component Interconnect)
and ISA (Industry Standard Architecture) buses.

A20 Digital Motherboard (for serial prefix MY433 and later)

A20 digital motherboard provides basic system control and interface functions for the
instrument. It contains a CPU, ROM for BIOS, 256MBytes RAM, USB interface, LAN,
keyboard and mouse interfaces, and interfaces to PCI (Peripheral Component Interconnect)
buses.

A21 Analog Interface Board

A21 analog interface board has several functions: an interface function between digital and
analog blocks, the other interface functions for A22 front panel keyboard, a power control
function, and measurement function. The A21 contains PLD (Programmable Logic
Device) for interface functions, a BNC connector for external trigger input, DSP (Digital
Signal Processor) for post measurement data processing and EEPROM that stores
correction constants for adjustment data.

A22 Front Panel Keyboard

A22 front panel keyboard detects operator's inputs, key inputs and RPG inputs, from the
front panel, and transmits them to the A21 analog interface board.

A24 GPIB Board

A24 GPIB board provides IEEE488 standard bus services for instrument. The board
interfaces the bus to A20 digital motherboard to receive and process GPIB commands.
A25 LAN Interface Board (for serial prefix JP1KH, JP2KH, and
MY432)
A25 LAN interface board allows the analyzer to communicate with an external controller
or an external server via a network interconnection. Protocol is TCP/IP, and it works for
10baseT and 100baseTX.

A26 Display Board

A26 display board controls LCD. The control signals are transmitted through a flat cable,
and a backlight voltage is supplied through A52 inverter board.
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