# Microprocessor and Computer Architecture

## How can you control LEDs using microprocessor via 82C55A PPI? Draw the interface diagram & write the necessary assembly codes.

Controlling LEDs Using Microprocessor VIA 82C55A: Using the 82C55A, we can control LED lights. We can use the pins of one port to connect with one leg of the LEDs and pins of another port to connect rest of the legs. Then we can program the 82C55A to control the LEDs. It can be done …

## What are the purpose of using command byte A and command byte B on 82C55A? Explain with suitable example.

Purpose of Using Command Byte A: Command byte A is used select modes, working functions of the ports. So the importance of using command byte A is that we can define on which mode it will be working on and which port will be used for which function such as input or output. For example, …

## What will be the arrangement of ports on 82C55A PPI for the following bit format of command byte A, 10000010

The given bit format is as follows, 7 6 5 4 3 2 1 0 1 0 0 0 0 0 1 0 Arrangement of Ports Due to Given Bit Format:             So the arrangement will be, mode 0, port A and C as output, port B as input.

## What will be the bit format of command byte A in 82C55A PPI for these arrangement, (i) Mode 0, Port A as input, port B and port C as output. (ii) Mode 1, port A as output, port B as input.

(i) Required Bit Format of command byte A:            So the bit format will be 10010000.           (ii) Required Bit Format of command byte A:  So the bit format will be 1010×11×.

## Draw the command byte A and command byte B of 82C55A PPI.

Command Byte A and Command Byte B:

## Draw the pin-out diagram of 82C55A PPI. How many modes you can select on 82C55A PPI? Explain.

Pin-Out Diagram of 82C55A: I/O Ports: It has three I/O ports, A, B and C. Each of these has 8 pins.             CS : This is used to select the 82C55A for programming and reading or writing.             A0 & A1: Register selection is done using the A0 and A1, which select …

## What is handshaking? Write a suitable example for handshaking with necessary assembly codes.

Handshaking:  Handshaking is a I/O control method to synchronize I/O devices with the microprocessor. As many I/O devices accepts or release information at a much slower rate than the microprocessor, this method is used to control the microprocessor to work with a I/O device at the I/O devices data transfer rate. Example:  Supposing that we …

## Write the differences between Isolated I/O and Memory Mapped I/O.

Memory Mapped I/O and Isolated I/O are two methods of performing input-output operations between CPU and installed peripherals in the system. Memory mapped I/O uses the same address bus to connect both primary memory and memory of hardware devices. Thus the instruction to address a section or portion or segment of RAM can also be used to address …