You are currently viewing What Is Computer Bus?

What Is Computer Bus?


 What Is a Computer Bus?

Without a computer bus, data transfer from devices to our computers will not be possible. The bus connects from devices to the CPU and CPU (memory) processor that sends data in the form of an electrical pulse. Buses come in many sizes. The size required depends on the “bits” being transferred. Common bus sizes are: 4 8 12 16 24 32 64 80 96 and 128 bits.


When talking about computer buses several terms explain exactly what the bus does and how it works. Bus speed is described in MegaHertz (Mhz). This is the speed of the data sent through the bus. 


The capacity of the bus is calculated by doubling the bus at its speed. However, this is not always accurate as many factors can slow it down. The internal bus can be found inside the CPU. This type of computer bus is capable of transmitting data instructions and other necessary information to other internal parts. 


The external system bus is located outside the processor but inside the computer. It also transfers data between a variety of computer parts. 


The computer bus used to actually transmit data is called the data bus. An internal data bus transmits data inside the processor and an external data bus transmits data from the processor to memory and vice versa. To make sure data is sent to their proper place there is an address bus. 


It contains all the destination information regarding the data being sent. If you combine a data bus with a computer bus address the process is called multiplication.


Over the years many different buses have been produced with several different manufacturers.

Bus ISA (Industry Standard Architecture) was produced in 1981. It started as an 8-bit bus at a speed of 4.77 Mhz. It was later upgraded to an 8.3-MHz 16-bit bus in 1984 along with IBM’s new processor the 80286.


The MCA (Micro Channel Architecture) produced in 1987 was a failed attempt at a computer bus. This 32-bit system bus was not able to be used with the other ISA computer buses that were already on the market. 


These were integrated with a new PS / 2 PC and Intel 80386 processors but were not accepted by other manufacturers.


A joint effort by AST Research Compaq Epson HP NEC Olivetti Tandy WYSE and Zenith Data Systems produced EISA (Architecture Standard). This was their response to the MCA. It was 8.3-bit megahertz backward compatible with ISA and could automatically configure an adapter card.


Using jumper switches the local VESA (Video Electronics Standards Association) bus was produced in 1992 to power the Intel 80486 processor. It was a 32-bit bus with 33 MHz.


The PCI buses introduced in 1993 were very popular due to the availability of Plug-n-Play devices. They are available in two versions: 32-bit 33 Mhz and 64-bit 66 Mhz. Several data sets could be transferred with these buses as they were able to check transfer errors and had a “burst mode”. These options have made these buses very fast.


Intel’s next move was to create a bus that helped transfer with 3D graphics. Introduced in 1997 the AGP (Accelerated Graphics Output) were buses that could improve video data performance in the computer system. 


This was possible because of their ability to separate normal data from video data at the time of transfer.


USB (Universal Serial Bus) are the newest versions of the computer bus driver architecture. It was a combined effort of Compaq DEC IBM Intern Microsoft NEC and North Telecom. They were released in 1996 along with the motherboard of the Intel 430HX Triton II. 


These buses transmitted data at 12 megabits per second (Mbps) and had the capacity to support 127 devices using only one IRQ. These buses are used to connect cameras CD drives keyboards mice printers scanners MP3 players and removable media.