Instruction Set of 8085

An Instruction is a command given to the computer to perform a specified operation on given data. The instruction set of a microprocessor is the collection of the instructions that the microprocessor is designed to execute. The instructions described here are of Intel 8085. These instructions are of Intel Corporation. They cannot be used by other microprocessor manufactures. The programmer can write a program in assembly language using these instructions. These instructions have been classified into the following groups:

1. Data Transfer Group
2. Arithmetic Group
3. Logical Group
4. Branch Control Group
5. I/O and Machine Control Group

Introduction to 8051 Microcontroller

• A microcontroller is a computer with most of the necessary support chips onboard. Microcontrollers can be embedded and are available in a variety of forms to suit practical applications.

• Number systems, such as binary and hexadecimal, are used in microcontroller applications. If decimal numbers are required they can be converted to binary and/or hexadecimal and vice versa.

• There are four classes of instructions namely: arithmetic, logical, data transfer and branch instructions.

• The microcontroller port pins may be required to sink and source currents.

• Time delays may be achieved by using register decrement instructions or by using onboard timer circuits.

• Using register decrement, longer delays can be achieved by the use of double or triple loops.