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

Show the transmission control protocol, Q. Show the Transmission Control Pr...

Q. Show the Transmission Control Protocol? Transmission Control Protocol (TCP) TCP makes Internet reliable. TCP solves many problems which can occur in a packet switching

The method(s) of payment for online consumers, The method(s) of payment for...

The method(s) of payment for online consumers are A) Electronic cash    (B) Credit/debit C) Electronic checks

Show basic types of transmission technologies, Q. What are the basic types ...

Q. What are the basic types of Transmission technologies, basis on which computer networks will be categorized? Ans: Broadly there are two kinds of transmission technology:

What is a parsing, what is parsin? Source programmed statements are ob...

what is parsin? Source programmed statements are observed as tokens, recognizing, building block of language the task of scanning the source statement and classifying the diff

What are batch systems, What are batch systems?  Batch systems are quit...

What are batch systems?  Batch systems are quite appropriate for implementing large jobs that need little interaction. The user can submit jobs and return later for the results

Illustrate about fat structure, Q. Illustrate about FAT structure? DOS ...

Q. Illustrate about FAT structure? DOS file system maintains a table of pointers known as FAT (File allocation table) that comprises an array of 16-bit values. There is one ent

Principles for developing successful system, Q. Principles for developing s...

Q. Principles for developing successful system? (1)  Both developers and customers must be involved for accuracy in the information. (2)  A problem solving approach must be

Sites are useful to the target audience members, Normal 0 false...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4 Select a range of a

Rational number expression evaluator, Develop a RPN rational number express...

Develop a RPN rational number expression evaluator (REEval). The learning objectives are: improved procedural programming skills improved confidence in designing and

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