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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Some of the pins of port C function as handshake lines. There is also a Control port from the Processor point of view. PC are used as handshake signals by Port A when configured in 8255 2. The functionality of the is now mostly embedded in larger VLSI processing chips as a intrl. Retrieved 3 June By using this site, you agree to the Terms of Use and Privacy Policy. Feedback Privacy Policy Feedback.

When CS Chip select is 0, is selected for communication by the processor. To use this website, you must agree to our Privacy Policyincluding cookie policy. Each port uses three lines from ort C as handshake signals.

D8255 – Programmable Peripheral Interface

This page was last edited on 23 Septemberat Auth with social network: Microprocessor And Its Applications. Its contents decides the working of The ‘s outputs are latched to hold the last data written to them.


Processor reads the status of the port for this purpose From Wikipedia, the free encyclopedia. Since the two halves of port C are independent, they may be used such that one-half is initialized as an input port while the itel half is initialized as an output port. The inputs are not latched because the CPU only has to read their current values, then store the data in a CPU register or memory if it needs to be referenced at a later time.

Acknowledgement and handshaking signals are provided to maintain proper data flow and synchronisation between the data transmitter and receiver. For port B in this mode irrespective of whether is acting as an input port or output portPC0, PC1 and PC2 pins function as handshake lines. Port A can be used for bidirectional handshake data transfer.

Each port can be programmed to function as simply an input port or an output port. So they are shown as X Required MD control word: Retrieved from ” https: Each line of port C PC 7 – PC 0 can be set or reset by writing a suitable value to the control word register.


Bidirectional Data Transfer This mode is used primarily in applications such as data transfer between two computers.

Intel – Wikipedia

Get code and repeat in infinite loop. Bit 7 of Port C. Inputs are not latched. They can be configured as either as input or output ports. Input and Output data are latched. If an input changes while the port is being read then the result may be indeterminate.

8255A – Programmable Peripheral Interface

This is required because the data only stays on the bus for one cycle. This means that data can be input or lntel on the same eight lines PA0 – PA7. Processor reads the port during the ISS. The features of the mode include the following: The is a member of the MCS Family of chips, designed by Intel for use with their and microprocessors and their descendants [1].

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