Bus what is

In most cases, the CPU and memory share signalling characteristics and operate in synchrony. The bus connecting the CPU and memory is one of the defining characteristics of the system, and often referred to simply as the system bus.

It is possible to allow peripherals to communicate with memory in the same fashion, attaching adaptors in the form of expansion cards directly to the system bus. This is commonly accomplished through some sort of standardized electrical connector, several of these forming the expansion bus or local bus. However, as the performance differences between the CPU and peripherals varies widely, some solution is generally needed to ensure that peripherals do not slow overall system performance.

Many CPUs feature a second set of pins similar to those for communicating with memory, but able to operate at very different speeds and using different protocols. Others use smart controllers to place the data directly in memory, a concept known as direct memory access. Most modern systems combine both solutions, where appropriate. As the number of potential peripherals grew, using an expansion card for every peripheral became increasingly untenable. This has led to the introduction of bus systems designed specifically to support multiple peripherals.

Common examples are the SATA ports in modern computers, which allow a number of hard drives to be connected without the need for a card. However, these high-performance systems are generally too expensive to implement in low-end devices, like a mouse. This has led to the parallel development of a number of low-performance bus systems for these solutions, the most common example being Universal Serial Bus. All such examples may be referred to as peripheral buses, although this terminology is not universal.

In modern systems the performance difference between the CPU and main memory has grown so great that increasing amounts of high-speed memory is built directly into the CPU, known as a cache. In such systems, CPUs communicate using high-performance buses that operate at speeds much greater than memory, and communicate with memory using protocols similar to those used solely for peripherals in the past.

These system buses are also used to communicate with most or all other peripherals, through adaptors, which in turn talk to other peripherals and controllers. Such systems are architecturally more similar to multicomputers, communicating over a bus rather than a network.

In these cases, expansion buses are entirely separate and no longer share any architecture with their host CPU and may in fact support many different CPUs, as is the case with PCI. What would have formerly been a system bus is now often known as a front-side bus. Other common categorization systems are based on the buses primary role, connecting devices internally or externally, PCI vs. SCSI for instance. However, many common modern bus systems can be used for both; SATA and the associated eSATA are one example of a system that would formerly be described as internal, while in certain automotive applications use the primarily external IEEE in a fashion more similar to a system bus.

The internal bus, also known as internal data bus, memory bus, system bus or Front-Side-Bus, connects all the internal components of a computer, such as CPU and memory, to the motherboard.

Internal data buses are also referred to as a local bus, because they are intended to connect to local devices. This bus is typically rather quick and is independent of the rest of the computer operations.

The external bus, or expansion bus, is made up of the electronic pathways that connect the different external devices, such as printer etc. Buses can be parallel buses, which carry data words in parallel on multiple wires, or serial buses, which carry data in bit-serial form. As data rates increase, the problems of timing skew, power consumption, electromagnetic interference and crosstalk across parallel buses become more and more difficult to circumvent.

One partial solution to this problem has been to double pump the bus. Often, a serial bus can be operated at higher overall data rates than a parallel bus, despite having fewer electrical connections, because a serial bus inherently has no timing skew or crosstalk. Multidrop connections do not work well for fast serial buses, so most modern serial buses use daisy-chain or hub designs.

The front side bus FSB is bi-directional bus. This is the most comprehensive and unique C omputer Science And Programming Fundamentals course Online which will give you in depth understanding of most important fundamental concepts in computer science And Programming.

Home About Course Contents 1. Introduction To Computer Science 2. Introduction To Computer System 2 A. How Computer Works? Binary Number System 4. Computer System Memory 4 A. Virtual Memory 4 B. What Is Machine Cycle? Intel Architecture 6. Computer Bus System 7. Operating System 9. Data Structures And Algorithms Computer Programming Fundamentals 10 A. Object Oriented Programming. Procedural Programming 10 C.

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What Is Control Unit? What Is Instruction Format? What Is Machine Instruction? Computer Bus. Introduction To Computer Bus. What Is Computer Bus? Table Of Contents. What Is Data Bus?

What Is Address Bus? Computer Bus Functions. Motherboard Bus Architecture. Types Of Computer Buses. What Is Control Bus? What Is System Bus? Bus Width And Bus Speed. What is Expansion Bus? Cable Buses. Motherboard Buses. Components being connected. Location of the components Internal bus And External bus. The computer system buses can be classified on the basis of type of the data being transmitted as : 1.

Data Bus , 2. Address Bus , 3. Control Bus. Computer Bus Types. The computer system buses can be classified on the basis of type of the components being connected as : 1. System Bus , 2. Expansion Bus , 3. Input And Output Bus. The computer system buses can be classified on the basis of location of the component being connected as : 1.

Internal Bus , 2. External Bus. Data Bus. Bus Architecture. However, with a serial bus, the data is transferred one bit at a time. With computer memory , a computer address bus is the bus containing the memory location memory address of where data is located in the computer memory.

Once the computer understands where to get the information, the data bus is used to transfer that data. A computer or device's bus speed is measured in MHz, e. The throughput of a bus is measured in bits per second or megabytes per second. Today, many of the buses listed above are no longer used or are not as common. Below is a listing of the most common buses and how they are used with a computer.

Home Dictionary B - Definitions. Why is a computer bus called a bus? Computer bus overview. Types of computer buses. Internal bus vs. Parallel bus vs.