1. The basic format of the command
1.1 Related concepts of machine instructions
Instruction Set (Instruction Set)
a collection of all machine instructions of a machine
- *Fixed-length instruction set
- All instructions in the instruction set are the same length!
- Simple instruction fetch control
- *Indefinite length instruction set
- All instructions in the instruction set have long and short lengths
opcode
(1) The length is fixed,
which is used when the instruction word length is long. RISC
such as IBM370 has an 8-bit opcode.
(2) The length is variable.
The opcode is scattered in different fields of the instruction word.
All instructions in the instruction set have long and short lengths.(3) Extended opcode technology
The number of opcode bits increases as the number of addresses decreases
Every reduction of one can constitute 24 more two-address instructions
address code
register operation
instruction word length
7.2 Types and Kinds of Operands
7.2.1 Operand types
storage method
7.2.2 Types of operation
- data transmission
- Arithmetic Logic Operations
- shift operation
- transfer
- input Output
7.3 Addressing modes
Determine the operand address of this instruction and the instruction address of the next instruction to be executed
instruction addressing
data addressing
7.3.1 Immediate addressing
7.3.2 Direct addressing
7.3.3 Implicit addressing
7.3.4 Indirect addressing
7.3.5 Register addressing
7.3.6 Base Addressing and Indexed Addressing
7.3.7 Relative addressing
7.3.8 Stack addressing
7.4 Examples
