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Computer / Embedded Bus Architecture

A bus, is a set of physical connections which can be shared by multiple devices in order to communicate with one another.

The purpose of buses is to reduce the number of pathways needed for communication between the devices, by carrying out all communications over a single data channel.


Early computer buses were literally parallel electrical wires with multiple connections, modern computer and embedded devices use both parallel and bit serial connections

Data Bus

It carries the data between the different components of the computer or embedded device.

The data transferred can be series or parallel, which allows the exchange of 1, 2, 4 or 8 bits or bytes of data at a time.  

Address Bus

It selects the route for the data to be transferred across the devices.

Control Bus

It decides that whether the data should be written or read from the data bus.

Expansion or I/O Bus

It is used to connect the computer’s peripheral devices such as printer, modem and scanner with the processor.

Timing

The bus provides a system clock signal to synchronize the peripherals attached to it with the rest of the system.

Important Bus Architecture Examples (Internal)


Parallel Communication

• ISA (Industry Standard Architecture)
• Multibus
• PCI (Peripheral Component Interconnect, Conventional PCI)
• IDE or PATA (Advanced Technology Attachment, ATA, Parallel ATA, EIDE, ATAPI)
• SCSI (Small Computer System Interface)
• AGP (Accelerated Graphics Port)
• VMEbus (VME, VERSAmodule Eurocard bus)
• cPCI (Compact PCI / PICMG 2.0)
• PC/104
• PCI-104
• PXI (PCI eXtensions for Instrumentation)
• VPX (VITA 446)

Serial Communication

• I²C (Inter-Integrated Circuit)
• SPI (Serial Peripheral Interface)
• PCIe (PCI Express)
• ExpressCard (Used in Laptops)
• SATA (Serial ATA)
• SAS (Serial Attached SCSI)

External

Parallel Communication

• GPIB (IEEE-488, General-Purpose Interface Bus)
• PCMCIA (PC Card)

Serial Communication

• RS-232 (EIA-232)
• RS-422 (EIA-422)
• RS-423 (EIA-423)
• RS-485 (EIA-485)
• Fire wire (IEEE 1394)
• Ethernet
• Fibre Channel
• InfiniBand
• CAN (Controller area network)
• FlexRay
• eSATA
• USB (Universal Serial Bus)