in a serial interface, each bit of data is transferred one bit after another down a single line.
in a parallel interface, multiple bit are transferred down parallel lines at the same time. parallel data transmission is clearly faster than serial data transmission.
Analogue to digital conversion
•A key job of interfaces is to convert the analogue signals that are sent in from peripherals to the digital form that the CPU can handle.
- Peripherals mainly work at higher voltage levels than the CPU. These signals need to be reduced to the CPU’s level and this is one of the jobs of the interface.
•For example, a signal coming from a keyboard at 9 V needs to be reduced to be reduced to a level which can be handled by the CPU, a maximum of 5 V.
Interface key points
•An interface is the hardware and associated software needed to allow communication between the processor and its peripheral devices and to compensate for any differences in their operating characteristics.
•The functions of an interface including buffering, data format conversion, voltage conversion, protocol conversion and the handling of status signals.
•Buffering involves holding data temporarily while it is in transit between the processor and the peripheral.
•Data format conversion involves changing the data received from the peripheral into a form that the processor can understand and vice versa.
•Serial data transmission sends the bits for each character in the data one after another along the same data line.
•Parallel data transmission sends each bit which makes up a character simultaneously along a separate data line.
•Voltage conversion is required when a peripheral operates using a different voltage form that used by the processor and its associated components on the motherboard of the computer.
•A protocol is a standard that enables the connection, communication, and data transfer between computers or between a computer system and a peripheral.
•Parity is an example of a protocol used during data transmission.
•The purpose of status information is to show whether or not a peripheral device is ready to communicate, that is, receive or to send data.