Buses, Basic Computer Science

BUSES

It can be seen from Figure 4 that there are three buses - the data bus, the address bus, and the control bus. Each bus consists of a group of parallel wires.

The data bus transfers data between memory, CPU and I/O units, under the control of signals sent through the control bus. For example, if data is to be transferred (sent) from the CPU to a memory location, the control unit within the CPU places an output instruction on the CPU, and write instruction on the memory unit. When the data arrives at the memory, it must be written into the memory at a given address. The address is already present, having been sent by the CPU along the address bus. Hence, data is stored at the memory address given. Note that if the transfer had been from the CPU to an I/O device, the address of the I/O device would have been given.

The address bus is one-way only. The control bus usually has one set of wires for input sensing lines, and one set for output controls.

Data buses are usually bi-directional; that is, data is either transferred, or fetched along the same set of wires. The control unit usually decides in which direction data will travel. If there are several peripherals, and these all wish to use the CPU at the same time, some method of priority must be established. There are various ways of achieving this. One method uses the control unit to select the lucky peripheral, whilst another method lets the peripherals themselves automatically decide which peripheral takes control.

1232_buses.png

Posted Date: 9/13/2012 6:51:04 AM | Location : United States







Related Discussions:- Buses, Assignment Help, Ask Question on Buses, Get Answer, Expert's Help, Buses Discussions

Write discussion on Buses
Your posts are moderated
Related Questions
Storage capacity and Cost per bit of storage: Storage capacit y:  It is the amount of data that can be stored in the storage unit. A large capacity is preferred.  Cost pe

Question 1 Explain boundary fill and flood fill polygon filling algorithm Question 2 Draw and explain the block diagram of typical workstation Question 3 Explain the ras

Optical Mark Recognition (OMR): OMR is the scanning of paper to detect the presence or absence of a mark in a predetermined position. Now days, it is used as an input device f

Ultrasonic Waves: Sound waves outside the audible range of humans. Ultrasonic waves consist of frequencies greater than 20 kHz and exist in excess of 25 MHz. Applications include i

I define a restricted form of TMs M as follows. Given any input x on the tape of M, the initial portion of the tape that holds x is read-only and one-way. That is, M cannot write o

I wrote a program that adds up 5x5 matrices by column and row. Now i have to use pointers to rewrite the same code how would do that


PRINCIPAL STRUCTURES IN FLOW CHARTING Structured programing calls for the usage of four principal structures to help simplify the program. They are:     Sequential contro

QUESTION 1 What are search engines? QUESTION 2 Write short notes on the inverted file. QUESTION 3 Write short notes on: (i) Derivative indexing (also known a