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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When CS Chip select is 0, is selected for communication by the processor.

Requires insertion of wait states if used with a microprocessor using higher that an 8 MHz clock. So, without latching, the outputs would become invalid as soon as the write cycle finishes. Processor reads the port during the ISS. To use this website, you must agree to our Privacy Policyincluding cookie policy.

Retrieved from ” https: Interrupt logic is supported. From Wikipedia, the free encyclopedia. To make this website work, we log user data and share it with processors. Interrupt logic is supported. Share buttons are a little bit lower.

D8255 – Programmable Peripheral Interface

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. Processor reads the status of the port for this purpose Each line of port C PC 7 – PC 0 can be set or reset by writing a suitable value to the control word register.

My presentations Profile Feedback Log out. Only port A can be initialized in this mode. We think you have liked this presentation. 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.

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Bit 7 of Port C. It is an active-low signal, i.

Microprocessor And Its Applications. About project SlidePlayer Terms of Service. Views Read Edit View history. Port A can be used for bidirectional handshake data transfer. The chip select circuit connected to the CS pin assigns addresses to the ports of Bidirectional Data Transfer This mode is used primarily in applications such as data transfer between two computers. Input and Output data are latched. This means that data can be input or output on the same eight lines PA0 – PA7.

As an example, consider an input device connected to at port A. This page was last edited on 23 Septemberat By using this site, you agree to the Terms of Use and Privacy Policy. The ‘s outputs are latched to hold the last data written to them.

Intel A Programmable Peripheral Interface

Published by Loraine Cobb Modified over 3 years ago. 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 damage of either the input device connected or or both, since both and the device connected will be sending out data.

This mode is selected when D 7 bit of the Control Word Register is 1. The Intel or i Programmable Peripheral Interface PPI chip was developed and manufactured by Intel in the first half of the s for the Intel microprocessor. This is required because the data only stays on the bus for one cycle. 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. The functionality of the is now mostly embedded in larger VLSI processing chips as a sub-function.


Each port uses three lines from ort C as handshake signals.

8255 PPI PPI Programmable Peripheral Interface.

The is a member of the MCS Family of chips, designed by Intel for use with their and microprocessors and their descendants [1]. For example, if port B and upper port C have to be initialized as input ports and lower port C and port A pppi output ports all in mode If an input changes while the port is being read then the result may be indeterminate. Some of the pins of port C function as ijtel lines.

PC are used as handshake signals by Port A when configured in Mode 2.

All of these chips were originally available in a pin DIL package. Its contents decides the working of PC are used as handshake signals by Port B when configured in Mode 1. Inputs are not latched.

Processor sends another byte to the port during 8525 ISS. Feedback Privacy Policy Feedback. Required MD control word: 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.

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