Arbiter and Interface
Circuits
By,
Visweish KM.
Arbitration
• There are occasions when two or more entities
contend for the use of a single resource in a
computer system.
• Arbiter circuit:
–The decision is usually made in an arbitration
process performed by an arbiter circuit.
Arbitration
• Arbitration:
– Arbitration refers to the process by which the current bus
master accesses and then leaves the control of the bus and
passes it to another bus requesting processor unit.
Arbitration for 3 Buses
• When one bus request is going on the other request
will be on hold
• All the requests will be granted on the basis of the
priorities
• When the request of one bus is deactivated, the other
request starts to execute
Interface Circuits
• An I/O interface consists of the circuitry required to
connect an input/oututdevice to a computer system.
• On one side of the interface have bus signals for
address,data and control
• On the other hand data path with its associated
controls.
I/O interface
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Storage buffer
Contains status flags
Address decoding circuitry
Performs any format conversion
Parallel Port
• It transfers data simultaneously to the device
• It uses multiple pin connector
• Circuit is simple
Parallel Port
• Parallel port is used to
send or receive data
having group of bits
simultaneously
• Parallel ports are classified
as:
– Input port
– Output port
Serial port
• It transmits and receives data one bit at a time
• For long diatances, it is convenient and cost
effective
• Capable of communication:
–Bit-serial on Device side
–Bit-parallel on Bus side