What is Bus (BUS)?

What is Bus (BUS)?

BUS (Bus) are circuits that enable data communication between all devices on the motherboard. That is, the circuits used to transmit data from one component of the computer to another are called Bus. All busses consist of two parts: Address bus and Standard bus. The capacity of the bus is important because it specifies how much data is transferred at once. When the standard bus transfers data about transactions performed on thecomputer, the address busdetermines where the data goes. Bus

Bus Hierarchy Most modern PCs have at least four bus services. Each is connected to the one at the next level, and each is slower than at the next level.

   1. Processor Bus: This bus is the highest-level bus that chipset uses to send information to and from the processor.
2. Cache Bus : A custom bus that high-level architectures use to access the cache.
3. Memory Bus: A Level 2 bus that connects memory subsysysms to chipsets or processors.
4. Local I/O Bus: It is a high-speed Input /Output bus that connects high-speed devices with memory, chipset, and processor.
5. Standard I/O Bus: Usually used for slower devices (mice, standard modems….)
Bus Bandwith: Bus Bandwith can theoretically be described as the amount of information that can be transferred over the bus in unit time.
Bus Speed: Bus speed corresponds to how many bits of information can be sent per second.
Bus Interfacing: Provided by bridges, which are part of the organizational chipset in the communication of devices with each other in systems with multiple bus.
Bus Mastering: High-bandwidth bus has a very large flow of information every second. As the standard method of data transfer, all types of information should be transferred through the processor, while some devices can provide direct information flow.
Devices that can control the bus are called Bus Mastering.
Although the PCI bus manages the bus in the computer world, it is possible that IDE/ATA hard disk drives can also manage the bus on PCI under certain conditions.
Local Bus:    The transition from text format to graphics format in the software world has led to an increase in the bandwidth of bus routes entering and exiting video cards in order to transfer large amounts of information with the transition to larger programs, as well as the concept of a larger and faster hard disk drive.

When the ISA busses being used at this time were inadequate to solve the problem, local busses that could be placed near or on top of the processor and that could approach the speed of the processor and become too slow between the processor and the devices began to be used. DATA TYPES

What is ISA (Industy Standard Bus Architecture)? The bus, which was first used in 1984, but ended a few years ago. It has an clock speed of 8 Mhzon the motherboard. It was developed in 1993 for cards running on ISA slots.

  • It is the first bus type produced.
  • It has black-colored nests.
  • It has a 16-bit bus width.
  • It is no longer produced.

What is PCI (Peripheral Pompenent Interconnect)?Bus

It is a bus type developed by Intel. PCI is the highest-performing road system used in today's desktops. This bus is available in 32 and 64-bit versions.

  • It has white-colored nests.
  • It has a larger slot than the ISA.
  • Supports Plug and Play.
  • They operate at 33 Mhz and 66 Mhz clock speed.
  • Supports LAN, SCSI, USB and other cards.

AGP (Advanced Grapich Port)

Bus AGP is the bus used only on video cards today. As applications such as 3D graphics and full-screen video evolve, a wider bandwidth is needed. The first version was released by Intel at the end of 1997 under the name'AGP specification 1.0'.It included both 1x and 2x speeds. 2.0 AGP 4X and 3.0 were 8X. In 2x AGP, the data flow rate is 533 MB/S. However, if the system bus speed is 66 MHz, 1x AGP is used on 66 MHz motherboards because the 2x AGP will take up all bandwidth and leave no room for other devices. It is compatible with 2x AGP as bandwidth on 100 MHz motherboards extends to 763 MB/S. AGP 4X : It is the 4X mode that is usually used today. Most motherboard manufacturers support this mode and use this technology on their motherboards, and at the same time all video card manufacturers are keeping up with this technology. In this mode, the AGP bus speed increased from 66 mhz to 100 mhz. This is a knowing data transfer speed that can be calculated in practically 800 MB/S. With the development of this technology, this speed has reached 1 GB/S

  • It is only used on video cards.
  • It is 32 bits of bandwidth.
  • It operates at a clock speed of 66 MHz. Total bandwidth is 266 MB/Sec.

What is PCI Express (Periheral Compenent Inter Express)?

A bus that provides connectivity between internal or external hardware on a computer. It is a bus that allows the maximum hardware to be added to it.

  • Provides data transmission at x16 speed. This means 16 paths, 4 GB/s bandwidth.
  • It has separate paths instead of shared paths, such as in PCI.
  • It has slots of X1, X4, X8 and X16.
  • They work much faster than PCI slots.


Bus Speed Chart