Computer structure
1. Computer Architecture
- Computer architecture refers to the general term of the theoretical components of the computer and the basic working principles and theories of the computer divided according to different attributes and functions. Among them, the theoretical component of the computer is not only linked to a certain actual hardware. For example, the storage part includes registers, memory, and hard disks.
Arithmetic unit
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The arithmetic unit is composed of the following four parts:
1. Arithmetic logic unit ALU: responsible for the main operations;
2. Accumulation register AC: its main function is to provide a work area for ALU to store temporary calculation results;
3. Data buffer register DR: responsible for data reading and writing;
4. Status condition register: the representation of the control status, such as the record of carry, overflow, and reset status (special: sometimes it is regarded as a part of the controller);
Controller
- The controller is composed of the following components:
1. Program counter PC: stores the address of the next instruction that the cpu will access, and records the number of instructions;
2. Instruction register IR: The instruction re-memory is read out and placed here for temporary storage;
3. Address basic device: record the address currently accessed by the cpu;
4. Instruction decoder: analyze and explain the opcode field in the instruction;
5. Timing components: provide timing control signals;
2. Classification of computer architecture – Flynn
Flynn's classification
In 1966, Michael.J.Flynn proposed to classify computer systems based on the polyploidy characteristics of instruction and data streams (usually called Flynn classification). The definitions of related concepts are as follows:
1. Instruction flow: Refers to the sequence of instructions executed by the machine.
2. Data flow: refers to the data sequence called by the instruction flow, including input data and intermediate results, but not including output data.
3. Polyploidy: refers to the maximum possible number of instructions or data in the same execution stage at the same time on the system performance bottleneck component.
According to different instruction flow and data flow organization methods, Flynn divides computer systems into the following four categories:
3. CISC and RISC
The main difference between CISC and RISC:
1. CISC has strong instruction capabilities. The use of single-major instructions is low but it increases the complexity of the CPU. Instructions are in variable-length format. Most of RISC instructions are single-cycle instructions. The instruction length is fixed. The operating registers are only Load/Store. Operating memory;
2. CISC supports a variety of addressing methods; RISC supports fewer methods;
3. CISC is realized through microprogram control technology, RISC adds general registers, hard-wired logic control is the main, and uses pipeline;
4. CISC Long development cycle;
5. RISC optimized compilation, which effectively supports high-level languages;