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

User interface (ui), Design a easy (text-based/ graphical) UI for  your pr...

Design a easy (text-based/ graphical) UI for  your program.  The user should be encouraged for  parameter values for  the particular protocol simulation. For  example, the user sho

Syntax and semantics - first-order logic, Syntax and Semantics: Propos...

Syntax and Semantics: Propositional logic is prohibited in its expressiveness: so just to represent true and false facts for the world. By a type of extending propositional lo

Subtract, Write the Add/subtract rule for floating point numbers. Ans:...

Write the Add/subtract rule for floating point numbers. Ans: a. Select the number with the smaller exponent and shift its mantissa right a number of steps equal to the differe

Depth first search - artificial intelligence, Depth First Search - artifici...

Depth First Search - artificial intelligence: Depth first search is very similar to breadth first, except for that the things are added to the top of this agenda rather than o

Java Applet, Simple codes for robot using applet

Simple codes for robot using applet

Program in c, addition c program for token separation

addition c program for token separation

Describe about pascaline, Q. Describe about Pascaline? Blaise Pascal ma...

Q. Describe about Pascaline? Blaise Pascal made very first attempt in the direction of automatic computing. He invented a device that comprised lots of gears and chains that us

C LANGUAGE PROGRAMME, find a c program to find the area under the curve y=f...

find a c program to find the area under the curve y=f(x) between x=a and x=b,intregrate y=f(x)between the limits of a and b.the area under a curve between two points can be found b

Explain parsing, What is parsing? The target of parsing is to find out...

What is parsing? The target of parsing is to find out the syntactic validity of a source string. A tree is built for use through subsequent phase of compiler, if the string is

Define memory latency, Define Memory Latency? It is used to refer to th...

Define Memory Latency? It is used to refer to the amount of time it takes to transfer a word of data to or from the memory.

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