communication between the A and the CPU. The A is a programmable peripheral interface. (PPI) device designed for use in Intel microcomputer. PPI is a general purpose programmable I/O device designed to interface the CPU with its outside world such as ADC, DAC, keyboard etc. We can program . PPI •The INTEL is a 40 pin IC having total 24 I/O pins. consisting of 3 numbers of 8 –bit parallel I/O ports (i.e. PORT A, PORT B.

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Its contents decides the working of Acknowledgement and handshaking signals are provided to maintain proper data flow and synchronisation between intle data transmitter and receiver. To make this website work, we log user data and share it with processors. Port A can be used for bidirectional handshake data transfer.

The inputs are not latched because the CPU only has to read their current values, pi store the data in a CPU register or memory if it needs to be referenced at a later time. Retrieved 26 July Processor reads the status of the port for this purpose Processor sends another byte to the port during the ISS.

D – Programmable Peripheral Interface

To use this website, you must agree to our Privacy Policyincluding cookie policy. They can be configured as either as input or output ports. Retrieved 3 June Only port A can be initialized in this mode. Auth with social network: Interrupt logic is supported. So they are shown as X Required MD control word: Port A uses five signals from Port C as handshake signals for data transfer.


Required MD control word: If an input changes while the nitel is being read then the result may be indeterminate.

If the Port interrupt is enabled, INT is activated. Interrupt logic is supported. Address lines A 1 and A 0 allow to access a data register for each port or a control register, as listed below:. There is also a Control port from the Processor point of view.

When CS Chip select is 0, is selected for communication by the processor. The features of the mode include the following: The two modes are selected on the basis of the value present at the D 7 bit of the control word register.

Intel – Wikipedia

Retrieved from ” https: For example, if port B and upper port C have to be initialized as input ports and lower port C and port A as output ports all in mode Published by Loraine Cobb Modified over 3 years ago. Each port uses three lines from ort C as handshake signals.

This interrupts the processor. The chip select circuit connected to the CS pin assigns addresses to the ports of Registration Forgot your password?


Intel 8255

Each port can be programmed to function as simply an input port or an output port. It is an active-low signal, i. So, without latching, the outputs would become invalid as soon as the write cycle finishes.

Microprocessor And Its Applications. Each line 82255 port C PC 7 – PC 0 can be set or reset by writing a suitable value to the control word register. Requires insertion of wait states if used with a microprocessor using higher that an 8 MHz clock. If you wish to download it, please recommend it to your friends in any social system.

Pip the two halves of port C are independent, they may be used such that one-half is initialized as an input port while the other half is initialized as an output port. Bit 7 of Port C.

If from intfl previous operation, port A is initialized as an output port and if is not reset before using the current configuration, then there is a possibility of damage of either the input device connected or or both, since both and the device connected will be sending out data.

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