Composition, Classification and Working Principle of Microprocessor

Ⅰ. The composition of the microprocessor

The microprocessor is composed of arithmetic logic unit, program counter, accumulator and general-purpose register group, data and address latch\buffer, timing and control logic unit, and internal bus. Among them, the arithmetic unit and the controller are its main components.

1. Arithmetic logic unit

The arithmetic logic unit ALU mainly completes arithmetic operations (+, -, ×, ÷, comparison) and various logical operations (and, or, not, XOR, shift) and other operations. ALU is a combinational circuit, which itself has no function of registering operands. Therefore, there must be two registers for storing operands: temporary register TMP and accumulator AC. The accumulator not only provides operands to ALU, but also receives the operation results of ALU.

The register array is actually equivalent to the RAM inside the microprocessor. It includes two parts, the general register group and the special register group. The general registers (A, B, C, D) are used to store the data, intermediate results or addresses involved in the operation.

They can generally be used as two 8-bit registers. With these registers inside the processor, frequent access to the memory can be avoided, the instruction length and instruction execution time can be shortened, the operating speed of the machine can be improved, and programming can also be brought convenience.

Special-purpose registers include program counter PC, stack pointer SP, and flag register FR. Their functions are fixed and are used to store addresses or address base values.

Program counter PC: used to store the address of the next instruction to be executed, so it controls the execution sequence of the program. Under the condition of executing instructions sequentially, every time a byte of the instruction is fetched, the content of PC is automatically incremented by 1.

Stack pointer SP: The stack pointer SP is used to store the top address of the stack. The stack is a specific area in memory. It works according to the "last in, first out" method. When new data is pushed into the stack, the original information in the stack remains unchanged, only the top position of the stack is changed. When the data is popped from the stack, the data at the top position of the stack is popped out. Automatically adjust the top position of the stack. That is to say, when data is pushed and popped, it is always at the top of the stack.

Flag register: used to store the result characteristics after the execution of arithmetic and logical operation instructions, such as when the result is 0, a carry or overflow flag is generated.

Internal bus: used to connect the various functional components of the microprocessor and transmit data and control signals inside the microprocessor.

Timing and control logic: It is the core control part of the microprocessor, which is responsible for controlling the entire computer, including fetching instructions from the memory, analyzing instructions, determining instruction operations and operand addresses, fetching operands, performing operations specified by instructions, sending Operation result to memory or I/O port, etc. It also sends corresponding control signals to other components of the microcomputer, so that the internal and external components of the CPU can coordinate their work.

2. I/O interface

The input/output interface circuit is an important component of a microcomputer. It is a logic control circuit for a microcomputer to connect external input and output devices and various control objects and exchange information with the outside world. Because the structure, working speed, signal form and data format of the peripherals are different, they cannot be directly connected to the system bus, and the input/output interface circuit must be used for intermediate conversion to realize information exchange with the CPU. 

I/O interfaces are also called I/O adapters, and different peripherals must be equipped with different I/O adapters. The I/O interface circuit is an essential part of the microcomputer application system.

The main function of the I/O interface is to realize the transmission of data between the internal computer and external devices. Through the I/O interface, the computer can receive data from external devices (input) and process it, and can also send processed data to external devices (output).

3. Memory

The memory of a microcomputer is used to store programs and data that are currently in use or are frequently used. The memory is divided into random access memory RAM and read-only memory ROM according to the way of reading and writing.

RAM is also called read/write memory, and the CPU can read or write its contents at any time during work. RAM is a volatile memory, that is, its contents will be lost after power off, so it can only store temporary programs and data.

The content of ROM can only be read and cannot be written, and the information stored in it remains unchanged after power off. It is a non-volatile memory. Therefore, ROM is often used to store programs and data of permanent files. Such as the initial boot program, monitoring program, basic input and output management program BIOS in the operating system, etc.

Storage can be divided into two categories, auxiliary storage (auxiliary memory) and primary storage (main memory).

Secondary Storage (Secondary Memory): Secondary storage is a storage device used for long-term storage of data and programs, such as hard drives, solid-state drives (SSD), optical discs, USB flash drives, etc. Auxiliary memory is characterized by large capacity and long-term data retention, but the read and write speed is usually slow.

Main memory (main memory): Main memory is the memory in a computer that is directly accessed by the central processing unit (CPU). It is usually made of high-speed random access memory (RAM), which is characterized by fast read and write speeds but loses data when power is turned off. The main function of the main memory is to store currently running programs and data for fast reading and writing by the CPU.

4. Bus

The bus is a common channel for transmitting information between various components in a computer system, and is an important component of a microcomputer. It is composed of several communication lines and various tri-state gate devices for driving and isolation.

The microcomputer always adopts the bus structure in the structural form, that is, the various functional components that constitute the microcomputer are connected through the bus. After adopting the bus structure, the relationship between the various functional components in the system is changed to a single relationship of each component facing the bus. As long as a component (function board/card) conforms to the bus standard, it can be connected to the system using this bus standard. , so that the reliability of the system function is improved.

Ⅱ. Classification of microprocessors

1. According to the application field

Microprocessors can be roughly divided into three categories: general-purpose embedded microprocessors, high-performance microprocessors and digital signal processors, and microcontrollers.

Embedded microprocessor: is a microprocessor designed for embedded systems. An embedded system is a computer system with a specific function or task, usually used to control and perform specific tasks. Embedded microprocessors have the characteristics of low power consumption, real-time performance, and high integration. 

High-performance microprocessor: Refers to a microprocessor that excels in computing power, processing speed, and performance. Common high-performance microprocessor architectures include RISC-V, x86-64, SPARC, ARMv8-A, and IBM POWER.

Digital signal processors, microcontrollers: Digital signal processors are mainly used to process digital signals, such as audio, video, images, communication signals, etc. They are widely used in communication systems, audio processing, image processing, radar, medical equipment and other fields. A microcontroller is a complete computer system that integrates a processor core, memory, input-output (I/O) interfaces, and peripheral controllers. They are usually used to control and perform specific tasks, such as embedded control, sensor interface, home appliance control, automotive control, etc.

2. According to the manufacturing process

2-bit microprocessor: The data bus width of the processor is 32 bits, and the address bus is usually also 32 bits.

64-bit microprocessor: The data bus width of the processor is 64 bits, and the address bus is usually 64 bits.

3. According to the instruction set architecture

Complex Instruction Set Computer (CISC): Uses a complex instruction set where each instruction can perform multiple low-level operations.

Reduced Instruction Set Computer (RISC): A simple, fixed-length instruction set with equal execution times for each instruction.

4. According to the number of core points

Single-core processor: Contains only one processing core and can execute only one instruction per clock cycle.

Multi-core processor: Contains multiple independent processing cores, each core can independently execute instructions to improve parallel processing capabilities.

5. According to performance and use

High-performance microprocessor: Focus on high-speed computing and large-scale tasks, used in high-performance computing, servers, etc.

Low-power microprocessor: Focus on energy saving and long battery life, used in mobile devices, embedded systems, etc.

Ⅲ. What is the working principle of the microprocessor?

A microprocessor fetches instructions from the computer's main memory (RAM). The Program Counter (Program Counter, PC) stores the address of the next instruction to be executed. The microprocessor sends the address in the PC to main memory for the next instruction.

Fetched instructions are binary data that the microprocessor decodes into executable operations. The decoder identifies instruction type, operand location, operation type, etc.

During the execution of instructions, if data needs to be read from memory or registers, the microprocessor will send the address of the data and read the data into the internal registers.

The microprocessor performs corresponding operations according to the decoded instruction type. This could be arithmetic operations, logical operations, data transfers, etc.

In some cases, after the instruction is executed, it is necessary to jump to a different instruction address according to the condition. Microprocessors implement jump and branch operations through control logic.

Ⅳ. What is the architecture of microprocessor? What are the different schema types?

The architecture of a microprocessor refers to its internal design and organization, including instruction sets, data paths, registers, and pipeline structures.

The types of schemas are:

1.Pipeline: Pipeline is a technology used to improve the execution efficiency of microprocessors. It divides the instruction execution process into multiple stages and allows multiple instructions to be executed in different stages at the same time, thus improving the instruction execution speed.

2. Control Unit: The control unit is responsible for the instruction decoding and execution control inside the microprocessor. It decodes instructions and controls the operation of the data path according to the instruction format and operation type defined in the instruction set architecture.

3. Instruction Set Architecture, ISA: The instruction set architecture defines the instruction set supported by the microprocessor, including the instruction format, operation type, operands, and addressing modes. The instruction set architecture determines the programming model and executable operations of the microprocessor.

4.Data Path: The data path refers to the path used to transmit and process data inside the microprocessor. It includes data registers, arithmetic logic unit (ALU), data bus, etc.

5.Registers: Registers are high-speed memories used to temporarily store data and instructions inside the microprocessor. Registers can be general-purpose registers, used to store data and intermediate results, or special-purpose registers, used to store control and status information.

Ⅴ. Manufacturing Process of Microprocessor

1. SOI (Silicon-On-Insulator): The SOI process uses an insulating layer to isolate the transistor and the substrate, reducing crosstalk and power consumption between transistors. It can provide higher performance and lower power consumption, especially suitable for high performance and low power consumption applications.

2. NMOS (N-type Metal-Oxide-Semiconductor): NMOS is a manufacturing process used in early microprocessors. It uses an n-type MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) as the basic building block. However, the NMOS process has high power consumption and has difficulties in manufacturing highly integrated processors.

3. FD-SOI (Fully-Depleted Silicon-On-Insulator): FD-SOI is a special SOI process that uses fully depleted transistors to provide higher performance and lower power consumption.

4. NMOS (N-type Metal-Oxide-Semiconductor): NMOS is a manufacturing process used in early microprocessors. It uses an n-type MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) as the basic building block.

5. FinFET (Fin Field-Effect Transistor): FinFET is a manufacturing process of a 3D transistor structure. It can provide better current control and lower power consumption than traditional planar transistors. FinFET processes are widely used in modern high-performance microprocessors.

6. BiCMOS (Bipolar Complementary Metal-Oxide-Semiconductor): The BiCMOS process combines the advantages of CMOS and bipolar transistors (Bipolar Transistor). It has advantages over traditional CMOS processes in terms of high-speed performance.

Ⅵ. Power Management of Microprocessor

The power consumption management of the microprocessor refers to effectively managing the power consumption of the microprocessor through various technologies and strategies. Power management aims to balance the relationship between computer performance and power consumption in order to improve the energy efficiency and energy saving of the system.

The main functions of the power management of the microprocessor are:

Thermal Management: Microprocessors may generate high levels of heat under high load. Thermal management techniques, such as heat sinks, fans, and temperature monitoring, keep the microprocessor's operating temperature within safe limits and avoid overheating hazards.

Power-Saving Sleep Modes: Microprocessors typically dynamically adjust their operating states based on current workloads and demands. When the processor is idle or under low load, it can enter an energy-saving sleep mode to reduce power consumption.

Core Shutdown: For multi-core processors, when some cores are idle, they can be shut down to reduce power consumption. This is usually controlled by the operating system or system management software.

Voltage scaling: Reducing the operating voltage of the microprocessor can significantly reduce power consumption. But lowering the voltage can also lead to performance degradation, requiring a trade-off between performance and power consumption.

Dynamic Frequency Scaling: The microprocessor can dynamically adjust the clock frequency according to the requirements of the workload.

Task scheduling and load balancing: The operating system can schedule tasks according to processor load conditions and energy management policies, and reasonably allocate tasks to different processing cores to achieve load balancing and energy efficiency optimization.

Ⅶ.What is the composition of a microprocessor?

Microprocessors are made from silicon, quartz, metals, and other chemicals. From start to finish, it takes about 2 months to make a microprocessor. Microprocessors are classified by the size of their data bus or address bus. They are also grouped into CISC and RISC types.

Ⅷ.What is the working principle of microprocessor?

The microprocessor fetches those instructions from the stored area (memory), then decodes it and executes those instructions till STOP instruction is met. Then, it sends the result in binary form to the output port.

Ⅸ.What is the construction and working of microprocessor?

A microprocessor is an integrated circuit (IC) which incorporates core functions of a computer's central processing unit (CPU). It is a programmable multipurpose silicon chip, clock driven, register based, accepts binary data as input and provides output after processing it as per the instructions stored in the memory.

X.What are the 5 types of microprocessors?

Microprocessors are classified into five types, namely: CISC-Complex Instruction Set Microprocessors, RISC-Reduced Instruction Set Microprocessor, ASIC- Application Specific Integrated Circuit, Superscalar Processors, DSP's-Digital Signal Microprocessors.