Concept and connotation
1.1. Basic CPU concepts
CPU is short for Central Processing Unit, which is the core of computing and control of a computer and is made up of ultra-large scale integrated circuits, including an operator, controller, cache memory, internal data bus, control bus and state bus input/output interface.
The main function of the CPU is to interpret computer instructions and process data in the computer software, to retrieve instructions from memory or cache memory, to decode them in the instruction registers, to decompose them into a series of micro-operations, to connect them to various CPU module components capable of performing the required operations, to send control commands and thus to complete the execution of the instructions.
The CPUs currently used in information technology systems are mainly microprocessors. A microprocessor is a central processing unit (CPU) implemented using a large-scale integrated circuit, usually in the form of a chip or a module in a chip SOC. Microprocessors can be broadly divided into three categories according to their application area: general purpose processors (MPUs, mainly used in high-end CPUs), microcontrollers (MCUs) and specialised processors. In this document the terms “microprocessor” and “CPU” are used indiscriminately unless otherwise stated.
1.2. Product classification
CPUs are a large family and can be classified by instruction set and application area.
1.2.1. Based on the instruction set
The instruction set is the binary encoding of the instructions executed by the CPU and is the specification for the interface between software and hardware. CPUs can be divided into CISC (Complex Instruction Set) and RISC (Reduced Instruction Set) according to their instruction sets.
(1) x86 architecture: dominating the desktop/server CPU market
The x86 architecture based on CISC (Complex Instruction Set) is a chip design system designed to facilitate programming and improve memory access efficiency, including two main features: first, the use of microcode, the instruction set can be executed directly in the microcode memory, the new design of the processor, only need to add fewer transistor circuits to execute the same instruction set, but also can quickly write new instruction set program; second, has a A large instruction set, x86 has a wide range of instruction types including dual operator format, register-to-register, register-to-memory and memory-to-register.
(2) ARM Architecture: The Rise of the Mobile Market
The ARM architecture, formerly known as the Advanced Thin Instruction Set machine, is a 32-bit thin instruction set processor architecture that is widely used in many embedded system designs and, in recent years, in the data centre server market due to its low power consumption and multi-core features. The main features of the early ARM instruction set architecture are: firstly, small size, low power consumption, low cost and high performance; secondly, extensive use of registers and most data operations are done in registers, resulting in faster instruction execution; thirdly, flexible and simple addressing methods and high execution efficiency; and fourthly, fixed instruction length, which allows for more efficient processing by means of multiple pipelines.
(3) RISC-V architecture: a new choice for the Internet of Things era
RISC-V is an open source instruction set architecture designed and released by the University of California, Berkeley, which aims to become the Linux of instruction set architectures, mainly for the Internet of Things (IoT), but can be extended to high-performance computing. -Some companies such as ZTE and Beijing Junzheng have already developed RISC-V based MCU chips. However, overall, as the RISC-V industry ecosystem is still relatively weak, there is still a long way to go for future development.
(4) MIPS architecture: RISC pioneer
MIPS is one of the most efficient and streamlined instruction set computer architectures. MIPS has three main advantages: Firstly, it has an early history of development, as it was widely used in servers and workstations in the 1990s. Secondly, MIPS has been widely influenced by the academic community, with computer architecture textbooks using MIPS as a practical example. Thirdly, MIPS is more open in terms of architecture licensing, the licensing threshold is much lower than x86 and ARM, and in 2019 there was a practical move to open up licensing, and MIPS allows licensees to change their own designs, extend instructions and allow secondary licensing.
(5) POWER Architecture: Retreating from History
The POWER architecture is a RISC processor architecture designed by IBM, POWER is unique in the mainframe sector, POWER3 is the world’s first 64-bit architecture processor, starting with copper interconnect and SOI (silicon on insulator) technology. The POWER3 was the world’s first 64-bit processor and began to use copper interconnects and SOI (silicon on insulator) technology, but POWER9 continued to deliver the highest performance with chaotic execution, intelligent threading and SMP (symmetric multiprocessing) hardware consistency.
1.2.2. Based on application areas
Microprocessors can be broadly classified into three categories based on their application areas: MPU (Micro Processor Unit), MCU (Micro Controller Unit) and special purpose processors, the CPU (Central Processing Unit) in this paper is a general purpose microprocessor.
(1) General purpose microprocessors
CPUs are usually classified according to the market for servers, desktops (desktops/laptops), supercomputers and so on. In addition, in recent years, network security and embedded applications also put high demands on CPU performance, and many network security and embedded systems use the same level of CPU as desktop and server.
MCU micro-controller is a low performance, low power consumption CPU for control applications, the main frequency of the CPU is generally less than 100MHz, usually the rate and specifications are appropriately reduced, and the memory, commonly used peripheral interface counters, USB, A/D conversion, UART, PLC, DMA and other peripheral interfaces, and even LCD driver circuit are integrated in a single chip, forming a chip-level computer, main frequency, power consumption can be very low, for different applications. The main frequency and power consumption can be very low, and different combinations of control can be made for different applications. MCUs are used in a large number of applications such as smart manufacturing, industrial control, smart home and remote control consumer applications, as well as in automotive electronics, industrial stepper motors and robot arm control.
(3) Specialised processors
A dedicated processor implements specific functions oriented towards a particular field. For example, the DSP (Digital Signal Processor), also known as a digital signal processor, is a microprocessor dedicated to digital signal processing operations, and its main application is the rapid implementation of various digital signal processing algorithms in real time. DSPs are widely used in digital control and motion control applications such as disk drive control, engine control, laser printer control, airbrush control, motor control, power system control, robot control, high precision servo system control and CNC machine tools. Other specialized processors include deep learning processors, database acceleration processors, security processors, brain-like computing chips, etc.
1.3. Industry Chain Supply Relationships
1.3.1. Upstream of the industry chain
The upstream of the CPU industry chain includes EDA-aided design tools and IP services that support integrated circuit design and manufacturing, semiconductor manufacturing equipment, and chip production and testing processes. At present, most of the upstream companies in the CPU industry chain are well-known foreign manufacturers with monopoly advantages, and the degree of localisation is low.
(1) EDA Aided Design Tools (Electronic design automaTIon)
EDA tools (Electronic Design AutomaTIon) are special software tools used to assist in chip design and are the foundation of the integrated circuit design industry.
EDA is highly complex software that requires years of accumulation. From the functional categories, EDA tools can be divided into: design automation software such as logic synthesis, layout and wiring; analysis and verification software such as simulation, timing analysis, physical verification, etc.. From the design object category, EDA tools can be divided into: analog circuit design software; digital circuit design software; process-aided design software, etc.
(2) IP services
IP cores, also known as Intellectual Property Cores, are circuit modules that have pre-designed functions and are reused in other systems. Instead of designing every detail of the chip, chip companies buy proven and reliable IP solutions to implement a particular function. This building block-like development model shortens the time for chip development and facilitates market capture.
(3) Semiconductor manufacturing equipment
Semiconductor manufacturing equipment is the basis of CPU chip manufacturing, the semiconductor manufacturing process includes silicon manufacturing, wafer manufacturing, packaging and testing three links, the entire manufacturing process in the highest proportion of wafer foundry equipment accounted for about 80%, testing equipment accounted for 8%, packaging equipment accounted for about 7%, silicon manufacturing equipment and other accounted for 5%.
(4) Chip production and testing process
In the chip production process, the main supply chain nodes include wafer flow, packaging and testing. In terms of flow, packaging and testing, the mainstream international companies are TSMC, Samsung, etc., with process levels up to 5nm. taking the flow chain as an example, the top ten global semiconductor flow foundries in 2019 are: TSMC, Samsung, Lattice, UMC, SMIC, TowerJazz, Huahong Semiconductor, VIS, PSC, DongbuHiTek. among them, the domestic manufacturers are The most advanced process is currently monopolised by Intel, TSMC and Samsung. The most advanced processes are currently monopolised by Intel, TSMC and Samsung, etc. Test bench R&D companies include Advantest and Hontec.