Agilent Technologies 8166A, B, 8163A, 8164A manual Status Model, Status Registers

The Status Model			Introduction to Programming
		The Status Model
		Status Registers
		Each node of the status circuitry has three registers:
		• A condition register (CONDition), which contains the current status.
		This register is updated continuously. It is not changed by having its
		contents read.
		• The event register (EVENt), which contains details of any positive
		transitions in the corresponding condition register, that is, when a bit
		changes from 0 → 1. The contents of this register are cleared when it is
		read. The contents of any higher-level registers are affected with regard
		to the appropriate bit.
		• The enable register (ENABle), which enables changes in the event
		register to affect the next stage of registers.
		The event register is the only kind of register that can affect the next stage
	N O T E
		of registers.
		The structures of the Operational and Questionable Status Systems are
		similar. Figure 4 describe how the Questionable Status Bit (QSB) and the
		Operational Status Bit (OSB) of the Status Byte Register are determined.
		Enable Registers
			To the
		OR	Condition Register
			of the Next Node

Event Registers

A positive transition in the condition register, when a bit changes from 0 → 1,

1 1 1 1 1 causes the corresponding bit of the corresponding event register

to change from 0 → 1.

Condition Registers

Figure 3 The Registers and Filters for a Node

Agilent 8163A/B, 8164A/B & 8166A/B Mainframes, Fifth Edition 33