1.13 - RISC/CISC

Catalog

One 、CISC： Complex instruction set computer

1、 thought

2、 Characteristics of instructions

3、 Addressing mode

4、 Realization way

Two 、RISC： Reduced instruction set computer

1、 thought

2、 Characteristics of instructions

3、 Addressing mode

4、 Realization way

5、 other

3、 ... and 、RISC/CISC Compare pictures （ Shorthand of examination site ）

Four 、 Examination site 1：RISC/CISC Characteristics

---

One 、CISC： Complex instruction set computer

1、 thought

• Further enhance the function of the original instruction ;
• Replace the original software subroutine with more complex new instructions , To complete the corresponding functions ;
• So as to realize the hardware of software functions ;

2、 Characteristics of instructions

• Number many ;
• Use frequency difference Big ;（ The command frequency of common functions will be higher ;）
• Variable length format ;（ The number of instructions used in each function is different , Therefore, it is impossible to realize these functions with a fixed length sequence of binary numbers , So the instruction is in the long format of the schedule ;）

3、 Addressing mode

• Support for multiple ;

4、 Realization way

• Microprogram control technology ;

Two 、RISC： Reduced instruction set computer

1、 thought

• By reducing the total number of instructions , To liberate the function of instructions ;
• Thus reducing the complexity of computer hardware design ;
• Enable instructions to be executed in a single cycle ;
• Through artificial optimization , Improve the execution speed of instructions ;
• So hard wiring logic is adopted ;

2、 Characteristics of instructions

• Number Less ;
• The frequency of use is close to ;（ Because they are basically used in a single cycle ;）
• Fixed length format ;
• Most of them are single cycle instructions ;
• Operation register ;
• Only Load/Store Operating memory ;

3、 Addressing mode

• There are few ways to support it ;

4、 Realization way

• The general register is added ;
• Hardwired logic control ;
• Adopt assembly line ;

（1） Super pipeline technology ： Refine the flow , Increase the level of the pipeline and improve the main frequency , Make the number of operations that can be completed per unit time more ;

（2） Superscalar Technology ： Multiple assembly lines , At the same time ;

（3） Ultra long instruction byte Technology ： Link many instructions together , So as to increase the operation speed ;

5、 other

• Optimize compilation , Support high level language effectively ;

3、 ... and 、RISC/CISC Compare pictures （ Shorthand of examination site ）

Four 、 Examination site 1：RISC/CISC Characteristics