Instruction is a statement in machine language and a set of meaningful binary codes. The basic format of an instruction is as follows: operation code field+address code field, where the operation code indicates the operation nature and function of the instruction, and the address code gives the address of the operand or operand.

The computers designed and produced by different computer companies are different in number and function, instruction format, addressing mode and data format, and even some commonly used basic instructions, such as arithmetic and logic operation instructions and transfer instructions, are different. Therefore, although the instruction set computing structure (RISC) is simplified to design the chip.

Extended data

In the 1970s, high-level language has become the main programming language for large, medium and small computers, and computer applications have become increasingly popular. Because the development of software exceeds the development of software design theory, the design of complex software system has not been well guided by theory, resulting in the quality of software can not be guaranteed, thus resulting in the so-called "software crisis."

People think that narrowing the semantic gap between machine instruction system and high-level language and providing a lot of support for high-level language are effective and feasible ways to alleviate the software crisis. Computer designers used the mature microprogram technology and the rapidly developing VLSI technology at that time to add various complex instructions for high-level languages, which made the instruction system more and more huge.

This is a traditional idea and practice to ensure and improve the effectiveness of instruction system when people design computers for decades.