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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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Input and Output data are latched. Only port A can be initialized in this mode. 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 From Wikipedia, the free encyclopedia.

The is a member of the MCS Family of chips, designed ibtel Intel for use with their and microprocessors and their descendants [1]. 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 other half is initialized as an output port.

Requires insertion of nitel states if used with a microprocessor using higher that an 8 MHz clock. Some of the pins of port C function as handshake lines. Each port uses three lines from ort C as handshake signals.

By using this site, you agree to the Terms of Use and Privacy Policy. Processor sends pli byte to the port during the ISS. PC are used as handshake signals by Port A when configured in Mode 2. Share buttons are a little bit lower. Acknowledgement and handshaking signals are provided to maintain proper data flow and synchronisation between the data transmitter and receiver. About project SlidePlayer Terms of Service. It is ingel active-low signal, i. The two modes are selected on the basis of the value present at the D 7 bit of the control word register.


Intel 8255

This is required because the data only stays on the bus for one cycle. To use this ontel, you must agree to our Privacy Inte,including cookie policy. Interrupt logic is supported. The ‘s outputs are latched to hold the last data written to them. Each port can be programmed to function as simply an input port or an output port.

In this mode, the may be used to extend the system bus to a slave microprocessor or to transfer data bytes to and from a floppy disk controller. We think you have liked this presentation. Port A can be used for bidirectional handshake data transfer.

Registration Forgot your password? The two halves of port C can be either used together as an additional 8-bit port, or they can be used as individual 4-bit ports.

PPI PPI Programmable Peripheral Interface. – ppt video online download

Bidirectional Data Transfer This mode is used primarily in applications such as data transfer between two computers. If from the 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 intle of either the input device connected or or both, since both kntel the device connected will be sending out data.

So they are shown as X Required MD control word: As an example, consider an input device connected to at port A. 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.


Retrieved from ” https: To make this website work, we log user data and share it with processors. Inputs are not latched. Input and Output data are latched. All of these chips were originally available in a pin Inte package. When CS Chip select is 0, is selected for communication by the processor. 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 pip it needs to be referenced at a later time.

When we wish to use port A or port B for handshake strobed input or output operation, we initialise that port in mode 1 port A and port B can be initilalised to operate in different modes, i.

They can be configured as either as input or output ports. My presentations Ppj Feedback Log out.

8255A – Programmable Peripheral Interface

Published by Loraine Cobb Modified over 3 years ago. Bit 7 of Port C.

Its contents decides the working of Processor reads the status of the port for this purpose It is used to interface to the keyboard and a parallel printer port in PCs usually as part of an integrated chipset. The functionality of the is now mostly embedded in larger VLSI processing chips as a sub-function. The chip select circuit connected to the CS pin assigns addresses to the ports of Retrieved 26 July Port A uses five signals from Port C as handshake signals for data transfer.

So, without latching, the outputs would become invalid as soon as the write cycle finishes. This interrupts the processor.