Agilent Technologies e4418b, e4419b Provide platform for the system software to run on, comprise

Theory of Operation

A2 Processor Assembly

	The microcontroller circuits that control all the above functions, and
	provide platform for the system software to run on, comprise the
	microcontroller itself, memory, and clock and logic circuits. The logic
	circuits have the function of ensuring the correct sequencing and decoding
	of the control signals for the various peripherals. The crystal oscillator
	clock circuit is buffered and distributed to the A4 interface assembly and
	the A5 daughter assembly. The program memory for the microcontroller is
	FLASH EEPROM to allow for in-circuit programming. The static RAM is
	split into volatile and non-volatile blocks, with the power for the
	non-volatile RAM being connected to the permanent (battery backed)
	power supply.
Note	It is advisable to replace the RAM battery A2BT1 every three
	years. If the battery fails or drops below 3 V the RAM will lose the
	following information when power is disconnected from the meter:

Unit Serial Number

Revision letter of Processor Card

Unit Option

User defined setups

User defined sensor calibration tables

4-6 Agilent E4418B/E4419B Service Guide