Intel G640T CM8062301002204 User Manual

Datasheet, Volume 2

13

This chapter contains the following:

• Register terminology
• PCI Devices and Functions on processor
• System address map
• Processor register introduction 
• Detailed register bit descriptions

 shows the register-related terminology and register attributes that are used 

in this document. Attribute modifiers are listed in 

RO

Read Only: These bits can only be read by software, writes have no effect. The value of the 

bits is determined by the hardware only.

RW

Read / Write: These bits can be read and written by software.

RW1C

Read / Write 1 to Clear: These bits can be read and cleared by software. Writing a '1' to a bit 

will clear it, while writing a '0' to a bit has no effect. Hardware sets these bits.

RW0C

Read / Write 0 to Clear: These bits can be read and cleared by software. Writing a ‘0’ to a bit 

will clear it, while writing a ‘1’ to a bit has no effect. Hardware sets these bits.

RW1S

Read / Write 1 to Set: These bits can be read and set by software. Writing a ‘1’ to a bit will 

set it, while writing a ‘0’ to a bit has no effect. Hardware clears these bits.

RsvdP

Reserved and Preserved: These bits are reserved for future RW implementations and their 

value must not be modified by software. When writing to these bits, software must preserve the 

value read. When SW updates a register that has RsvdP fields, it must read the register value 

first so that the appropriate merge between the RsvdP and updated fields will occur.

RsvdZ

Reserved and Zero: These bits are reserved for future RW1C implementations. SW must use 

0 for writes.

WO

Write Only: These bits can only be written by software, reads return zero. 
Note: Use of this attribute type is deprecated and can only be used to describe bits without 

persistent state.

RC

Read Clear: These bits can only be read by software, but a read causes the bits to be cleared. 

Hardware sets these bits. 
Note: Use of this attribute type is only allowed on legacy functions, as side-effects on reads are 

not desirable.

RSW1C

Read Set / Write 1 to Clear: These bits can be read and cleared by software. Reading a bit 

will set the bit to ‘1’. Writing a ‘1’ to a bit will clear it, while writing a ‘0’ to a bit has no effect.

RCW

Read Clear / Write: These bits can be read and written by software, but a read causes the 

bits to be cleared. 
Note: Use of this attribute type is only allowed on legacy functions, as side-effects on reads are 

not desirable.