data bus, address bus and control bus

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a bus is a pathway for a digital signal to rapidly move data

there are three internal buses associated with the processors: the data bus. the address bus, the control bus.

together these three make up the system bus. the system bus is internal bus intended to connect the processor with internal hardware devices

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data bus

width is typically 8,16,32 or 64 bits.

the width of thedata bus reflects the maximum amount of data that can be processed and delivered at one time.

a 64 bit processor has a 64 bit data bus and can communicate 64 bits of data at a time

the width of data bus of any processor indicates its simultaneous handling capacity of maximum number of bits.

data bus is basically a bidirectional bus

data flow mechanism

note that D0-D7 represents data bus interfaced with processor

each flipflops are storage of data and output of each flipflops, tristate buffers are providerd whose control inputs are connected in parallel

the location selects signals from the decoder within the memory ic along with memory read or write signal enable these buffer

the clock signal select the signal for the storage operation

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address bus

the physical location of data in memory is carried by address bus.

the address bus carries only the information regarding the address, and is synchronized with the data bus to accomplish read or write task from the processor

the address us is only as wide as is necessary to address all memory in the system

if there are n address bus the size of the memory is 2^n

address bus is always unidirectional.

address bus and addressing

the width of the address bus or number of address lines available from any processor indicate its maximum memory size handling capacity

the number of memory locations addressed by n address lins is 2^n

therefor the processor offers 16 address lines then it can address 2^16 or 64 locations

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control bus

the control bus carries control information from control units to other units

the control units is used for directing the activities of all units

for example whether the data is read or written is determined by the control bus

to important control bus are read and write

condition of these control signal indicates whether the processor is expecting data in or sending the data out.