What is the purpose of Programmable Peripheral Interface 8255A? Explain about its different ports.

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Suresh Chand · Accepted Answer

The Programmable Peripheral Interface (PPI) 8255A is an integrated circuit that is used to interface input/output devices with a microprocessor. It is a versatile device that can be programmed to work in different modes to meet the requirements of various input/output devices. The 8255A has three ports, Port A, Port B, and Port C. Each port can be used as either an input port or an output port, depending on the programming mode. Port A: Port A is an 8-bit bidirectional port that can be used for input or output operations. It can be programmed to work in two modes, Mode 0 and Mode 1. In Mode 0, Port A is used as two 4-bit input ports, while in Mode 1, it is used as one 8-bit input or output port. Port B: Port B is an 8-bit bidirectional port that can also be used for input or output operations. It can be programmed to work in three modes, Mode 0, Mode 1, and Mode 2. In Mode 0, Port B is used as two 4-bit input or output ports. In Mode 1, it is used as one 8-bit input or output port. In Mode 2, it is used as two 8-bit input or output ports, with one port being used for the high-order bits and the other for the low-order bits. Port C: Port C is a 4-bit port that can be used as either an input or output port. It can be programmed to work in two modes, Mode 0 and Mode 1. In Mode 0, Port C is used as four 1-bit input or output ports. In Mode 1, it is used as two 2-bit input or output ports, with one port being used for the high-order bits and the other for the low-order bits. In addition to the three ports, the 8255A also has control registers that are used to program the device. These include Control Register A (CRA), Control Register B (CRB), and Control Register C (CRC). These registers are used to set the operating modes of the ports, configure the interrupt system, and perform other functions. The purpose of the 8255A is to provide a flexible and configurable interface between a microprocessor and input/output devices. It allows for different modes of operation to be programmed, depending on the specific requirements of the input/output devices. By using the 8255A, input/output devices can be easily interfaced with a microprocessor, without the need for complex circuitry or custom hardware.

What is the purpose of Programmable Peripheral Interface 8255A? Explain about its different ports.

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What is the purpose of Programmable Peripheral Interface 8255A? Explain about its different ports.

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