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

Explain clr, What is CLR?  CLR(Common Language Runtime) is the major r...

What is CLR?  CLR(Common Language Runtime) is the major resource of .Net Framework. It is collection of services like garbage collector, exception handler, jit compilers etc. w

Branding choices, Develop a web traffic plan - suppose that there is no/min...

Develop a web traffic plan - suppose that there is no/minimal advertising budget so you will require to look at branding choices & site design, word-of-mouth and publicity as your

View the site files, To see a high-level representation of the structure of...

To see a high-level representation of the structure of a local site, you use Dreamweaver's Site Map view. You can also use site map to add new files to the site, to add, remove and

Write the command to show the ip host table, show hosts is the command whi...

show hosts is the command which display the IP host table

Explain binary number system, Explain Binary number system. Ans. Bi...

Explain Binary number system. Ans. Binary Number System The number of system along with base or Radix two is termed as the Binary Number System. To show the number, 0 a

Define the term- verification, Define the term- Verification It is a wa...

Define the term- Verification It is a way of preventing errors when data is copied from one medium to another (for instance from paper to disk/CD or from memory to DVD, etc.).

Define about classes of object oriented modelling, Define about classes of ...

Define about classes of object oriented modelling A class is a collection of things, or concepts that have the same properties. Each of these concepts or things is known an obj

Explain about barrier, Q. Explain about Barrier? Barrier: No actual tra...

Q. Explain about Barrier? Barrier: No actual transfer of data takes place in this mode unless all the processors involved in the communication execute a particular block, calle

What is a system call, What is a system call? A  system  call  is  a  r...

What is a system call? A  system  call  is  a  request  made  through  any  program  to  the  operating  system  for performing tasks, picked by a predefined set, that the said

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