Computer bus, is a communication system that transfers data between components inside compute System.

Computer buses are group of lines that carries data,address or control signals.It is a subsystem that transfers data between computer components inside a computer or between computers.The CPU Bus has multiplexed lines, i.e., same line is used to carry different signals.The CPU interface is provided to demultiplex the lines, to generate chip select signals and additional control signals.

In computer architecture There are three types of buses,

Address bus :
It carries the address of a unique memory or input/output (I/O) device.The address bus is ‘unidirectional’.The size (width) of the address bus is specified by the number of bits it can handle.A 16 bit address bus is capable of addressing 65,536 (64K) addresses.

Data bus :
It carries data stored in memory (or an I/O device) to the CPU or from the CPU to the memory (or
I/O device).The data bus is ‘bi-directional’.Depending on the particular microprocessor, the data bus can handle 8 bit or 16 bit data.

Control bus :
It is a collection of control signals that coordinate and synchronize the whole system.The control bus is used by the microprocessor to send out or receive timing and control signals in order to coordinate and regulate its operation and to communicate with other devices, i.e. memory or input/output.

Computer BUS

Today all computers utilize two bus types,

Internal bus or local bus
External bus or expansion bus

An internal bus also known as internal data bus enables communication between internal components  of a computer, such as CPU and memory, to the motherboard .

An external bus is composed of electrical circuits which enable connection  with external components such as a USB or SCSI device.

IDE Cables

IDE is Integrated Drive Electronics, is a standard type of connector in a computer.IDE is a types of cables which connect some hard drives and optical drives to motherboard, one end of cable is connected to motherboard and other end is connected to hard drive or optical drive

IDE cable have three connection in it , one is connect in motherboard and other two is for connecting drive.

IDE cable


PATA stands for parallel ATA.
SATA stands for Serial ATA.

There are two types of hard drive connections that a computer could have: Parallel ATA (PATA), and Serial ATA (SATA). Now a day we used SATA.

PATA is capable of data transfers speeds of 66/100/133 MBs/second, whereas SATA is capable of 150/300/600 MBs/second. The max length of a PATA cable is 18-inches, whereas a SATA cable can be up to 3.3 feet (1 meter) in length.SATA cables are also smaller in size than a PATA cable.

SATA is much faster than PATA.SATA drives are hot pluggable while PATA drives are not.SATA uses smaller cables than PATA.


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