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 the basic syntactic constructs through reductions, Recognition of b...

Recognition of basic syntactic constructs through reductions, this task is performed by? By Syntax analysis, recognition of fundamental syntactic constructs through reductions

What is the accessibility testing, Accessibility testing for web sites is a...

Accessibility testing for web sites is a service that can give much more than the standard point-by-point testing methods of most automated services.

Computational study of a spring-mass system, Idealized spring-mass systems ...

Idealized spring-mass systems have numerous applications throughout engineering. Fig.1 shows an arrangement of three masses and four springs which, after is released, is pulled dow

Operating system., what is the minimum number of page faults for an optimal...

what is the minimum number of page faults for an optimal page replacement strategy?

The interface chip design, This is an embedded system that involves the int...

This is an embedded system that involves the integration of hardware and software design stages. It consists of the user interface (keypads and LCD display) and two Peripheral Inte

Differentiate between the serial port and parallel port, Question: (a) ...

Question: (a) Provide types of computer systems and briefly describe each one. (b) With the help of example, explain the difference between open source software, freeware a

State about dynamic modelling and its inputs, State about Dynamic modelling...

State about Dynamic modelling and its inputs Dynamic modelling is elaborated further by adding concept of time: new attributes are computed, as a function of the attribute chan

Cim and holonic manufacturing system, CIM and Holonic Manufacturing System ...

CIM and Holonic Manufacturing System The improvement of computer integrated manufacturing has demonstrated that the automation has the same potential such that of computers in

Build a tv remote control, Communication by devices, such as the HC11 proce...

Communication by devices, such as the HC11 processor, is a key and vital part of most systems that are used in military, commercial, and academic settings.  In fact, most of these

What are the properties of electronic cash, What are the properties of elec...

What are the properties of electronic cash? Properties: 1. Monetary Value: Monetary value should be backed by bank certified cashier’s cheque or cash, bank authorized cred

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