Address phase - computer architecture, Computer Engineering

Assignment Help:

Address phase:

A PCI bus transaction starts having an address phase. The initiator,  after seeing that it has GNT# and the bus is inactive, drives the target address onto the AD[31:0] lines, the associated command (for example: I/O write or memory read,) on the C/BE[3:0]# lines, and pulls FRAME# low.

Each other device inspect the address and command & decides whether to respond as the target by asserting DEVSEL#. Device has to respond by asserting DEVSEL# within 3 cycles. Devices which promise to respond within one or two cycles are said to have "fast DEVSEL" or "medium DEVSEL", respectively. (In fact, the time to respond is 2.5 cycles, since PCI devices have to transmit all signals half a cycle early so that they can be retaining3 cycles later.)Note that a device have to latch the address on the first cycle; the initiator is needed to remove the address and command from the bus on the following cycle, even before retaining a DEVSEL# response. The extra time is available only for interpreting the address and command after it is captured. On the fifth cycle of the address phase (or earlier if all other devices have medium DEVSEL or faster), a catch-all "subtractive decoding" is permitted for some address ranges. It is generally used by an ISA bus bridge for addresses within its particular range (16 bits for I/O and 24 bits for memory).

On the sixth cycle, if there has been no response, the initiator can abort the transaction by deserting FRAME#. It is known as master abort termination and it is customary for PCI bus bridges to return all- ones data (0xFFFFFFFF) in this particular case. PCI devices therefore are generally designed to ignore by using the all-ones value in essential status registers, so that such type of error may be easily detected by software.

 


Related Discussions:- Address phase - computer architecture

Full form of www, What do you understand by WWW WWW: The World Wide ...

What do you understand by WWW WWW: The World Wide is an architectural framework for accessing linked documents increase out over thousands of machines all over the world. It

Determine the advantages of bcd adder, Determine the advantages of BCD Adde...

Determine the advantages of BCD Adder Now let us see the arithmetic addition of two decimal digits in the BCD, with a possible carry from previous stage. As each input digit do

What about page footer, By default, this page is quite barren. Though, go e...

By default, this page is quite barren. Though, go explore the Query Page some more; you will search that you can store numerous queries on the server, so if you regularly run a cer

Message passing programme development environment, In a multicomputer syste...

In a multicomputer system the computational load amid different processors should be balanced.  To pass information between different nodes message passing technique is used. The p

What is a data class, What is a Data Class? The Data class verifies in ...

What is a Data Class? The Data class verifies in which table space the table is stored when it is formed in the database

Depth - basic characteristics of an experts system, An expert system has d...

An expert system has death that is it operate effectively in a narrow domain containing difficult challenging problems. Thus the rules in an experts systems are necessarily co

Explain that lost acknowledgement in packet retransmission, Explain that th...

Explain that the lost acknowledgement does not necessarily enforce retransmission of the packet . To guarantee reliable transfer, protocols utilize positive acknowledgement al

What is gui status, What is GUI status? How to create /Edit GUI status? ...

What is GUI status? How to create /Edit GUI status? A GUI status is a subset of the interface elements used for a certain screen. The status comprises those elements that are c

Characteristics of extreme unencoded micro-instructions, Q. Characteristics...

Q. Characteristics of extreme unencoded micro-instructions? 1. Two sources can be attached by respective control signals to a single destination; though only one of these sourc

Weka uses a gaussian - radial basis function, A data set with 1000 rows is ...

A data set with 1000 rows is input to a neural network in Weka. The test option is set to 10-fold cross validation and the neural network option validationSetSize = 20%. How many r

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd