Interfaces A peripheral sends and/or receives data at a certain speed and

using a certain format.

The CPU and/or the device receives data at a certain speed and using a certain format.

An interface is a unit that sits between the CPU and a peripheral device and compensates for the differences in speed, codes etc. to ensure compatibility.

COMPUTERDEVICE INTERFACE

Status Information The interface can provide information on the status of the

peripheral

Printer – ready / out of paper / jam Network – data sent and received MIDI – data received

Data Conversion A CPU will work with data using different formats and speeds than

peripherals

For example, the processor will be able to send data to the printer at a speed faster than printer can handle it

Data may be sent / received in serial or parallel format

Parallel Serial

ProtocolThe processor and peripheral require a set of rules so that they know how to communicate with each other. These rules are known as a protocol.

The protocol will include:the type of error checking to be useddata compression method, if anyhow the sending device will indicate that it has finished sending a messagehow the receiving device will indicate that it has received a message

Data StorageWhat happens if the processor wants to send/receive data to/from a peripheral which handles data at a different speed?

e.g. a printer can only print 5 pages per minuteA hard drive can only write at 70 megabytes per secondA microphone captures data at a speed faster than the processor can process it

Data StorageWhat happens if the processor wants to send/receive data to/from a peripheral which handles data at a different speed?

e.g. a printer can only print 5 pages per minuteA hard drive can only write at 70 megabytes per secondA microphone captures data at a speed faster than the processor can process it

In cases like this, the problem would be that the processor or peripheral would have to wait until the job was finished unable to carry out any other tasks.

Data StorageWhat happens if the processor wants to send/receive data to/from a peripheral which handles data at a different speed?

e.g. a printer can only print 5 pages per minuteA hard drive can only write at 70 megabytes per secondA microphone captures data at a speed faster than the processor can process it

In cases like this, the problem would be that the processor or peripheral would have to wait until the job was finished unable to carry out any other tasks.

Buffers and spoolers provide the solution to this problem