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Unformatted text preview: a Computer Bus
Data lines are collectively called data bus. They provide paths for moving system modules such as processor, memory and I/O ports. Data buses are typically composed of 8, 16, or 32 separate lines, so that the number of lines are referred to as the width of data bus. Ali Raza Computer Bus
As each line can carry only one bit at a time, the number of lines determines how many bits can be transferred at a time. Width of data bus is thus a key factor in determining the overall performance of a system as the data transfer rate is dependent upon it. E.g. in case when data bus is 8 lines wide, the processor must access the memory module twice to have a 16 bits long instruction, whereas for 16 lines wide data bus, the processor will access the memory module only once. Data buses are bidirectional in nature. Ali Raza Computer Bus
Like data lines, address lines are also bidirectional in nature and are collectively called address buses. These lines are used to designate the source or destination of data that is to be carried by the data bus. E.g. if the processor wants to read an instruction or data of 8 or 16 or 32 bits from the memory, it puts the address of the desired memory location on the address lines contained in an address bus. The width of the address bus determines the maximum possible capacity of system’s memory. Similarly, address bus may also be used to address I/O ports. Ali Raza Computer Bus
Unlike data and address lines, control lines are unidirectional in nature and are collected together in the form of control bus. These lines are used to control access to data as well as the use of data and address lines. Control signals transmit information about both command and timings between system modules (i.e. processor, memory, and I/...
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This document was uploaded on 03/16/2014.
- Spring '14