input device with the output device or vice-versa. In order to make it simpler, Intel has designed A chip to interface I/O devices. The Intel A is a general. A Programmable Peripheral Interface in Microprocessor – A Programmable Peripheral The following figure shows the architecture of A −. The (or i) programmable peripheral interface (PPI) chip was developed and manufactured by Intel The PPI chip Architecture.

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It consists of data bus buffer, control logic and Group A and Group B controls. Aechitecture bit 7 of the control word is a logical 1 then the will be configured. Each of the Group A and Group B control blocks receives control words from the CPU and issues appropriate commands to the ports associated with it.

It is an active-low signal, i. Read operation of the Control Word Register is allowed. The ‘s outputs are latched to hold the last data written to them. Retrieved 26 July Mode O Basic Functional Definitions: Intel Programmable Interval Timer. 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 In architecyure, a response from the peripheral device indicating that it has received the data output by CPU.


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Digital Communication Interview Questions. This means that data can be input or output on the same eight lines PA0 – PA7. Analog Communication Interview Architectrue.

8255A Programmable Peripheral Interface Microprocessor

The Control Word Register can only be written into. This port can be divided into two 4-bit ports under the mode control. A architevture on this input pin enables the communcation between the and the CPU. Explain with block diagram working of PPI. The input pins for the control logic section are described here.

Explain with block diagram working of PPI.

Evolution of Microprocessor History of the microprocessor! So, without latching, the outputs would become invalid as soon as the write cycle finishes.

The control word contains information such as “mode”, “bit set”, “bit reset”, etc. Embedded Systems Practice Tests. Download our mobile app and study on-the-go. Each 4-bit port contains a 4-bit latch and it can be used for the control signal output and status signal inputs in conjunction with ports A and B.

This tri-state bi-directional buffer architedture used to interface the internal data lilts of to the system data bus. 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. The is also directly compatible with the Z, as well as many Intel processors. From Wikipedia, the free encyclopedia.


8255 Programmable Peripheral Interface

It can be programmed in three modes: All of the output registers, including the status flip-flops, will be reset whenever the mode is changed. A “high” on this input initializes the control register to 9Bh and all ports A, B, C are set to the input mode.

Data is transmitted or received by the buffer upon execution of input or output instructions by the CPU. During the execution of the systems program any of the other modes may be selected using architeecture single output Instruction.

Control words and status information are also transferred through the data bus buffer. All Mask flip-flops are automatically reset during mode selection and device reset. Analog Communication Practice Tests.

Port C can be spitted into two parts and each can be used as control signals for ports A and B in the handshake mode.