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

Invoke on the dataadapter control, Which method do you invoke on the DataAd...

Which method do you invoke on the DataAdapter control to load  your generated dataset with data? DataAdapter.Fill(ds). The beauty of this method is it automatically implicitly

Describe clusters in cellular systems, Question: a) With the help of a...

Question: a) With the help of a diagram, describe clusters in cellular systems. b) Describe the role of the following components in the GSM architecture Radio Sub-Sy

Give the decription of user case, Give the decription of user case A us...

Give the decription of user case A use case is a description of the set of the sequence of actions which a system performs to produce an observable result which is of a value t

What is switched mode power supply, Q. What is Switched Mode Power Supply? ...

Q. What is Switched Mode Power Supply? SMPS is the unit into which electric supply from the mains is connected to your PC and this supplies DC to internal circuits. It is more

How to turn on the session support in php, The session support can be turne...

The session support can be turned on automatically at the site level, or manually in every PHP page script: * Turning on session support automatically at the site level: Set s

Describe about directory in doc, Q. Describe about directory in DOC? We...

Q. Describe about directory in DOC? We all know that, the volume of the hard disk is generally quite large (10 MB to a few GB). You can keep hundreds or even thousands of files

Asp.net, how work for asp.net

how work for asp.net

What do you mean by u-area or u-block, What do you mean by u-area (user are...

What do you mean by u-area (user area) or u-block? This having the private data that is manipulated only by the Kernel. This is local to the Process, i.e. every process is a

What is the linkage section, The linkage section is part of a known as prog...

The linkage section is part of a known as program that 'links' or maps to data items in the calling program are working storage. It is the part of the called program where these sh

recycling from e-waste to resources , Make at least 6 web pages with good ...

Make at least 6 web pages with good formatting, color balance and presentation on any one of the following topics:- 1.    Recycling from E-waste to resources 2.    Light and So

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