Siheyuan starts from the stationmaster

Heung Kong's electronic technology industry has only emerged in recent years, and many graduates of Heung Kong who aspired to work in the electronic technology industry in the early days had to go out to seek development.They grew up eating Cantonese cuisine and speaking Cantonese, so they may not be able to adapt to places such as Wanwan, Singapore, John's Country, Beautiful Country and Wa Country.

If there is a Xiangjiang company willing to provide the same treatment and development conditions, I believe that the engineers from Xiangjiang who make a living abroad will be willing to return to work in a city they are more familiar with and kind to.Bai Zirui let the human resources department and public relations department of the group company carry out these tasks in an orderly manner.

After Bai Zirui took care of the company's affairs, he focused most of his energy on a RISC (Reduced Instruction Set) development project team established in cooperation with Professor Yao Zhaoming, the director of the semiconductor laboratory.

The reduced instruction set is a design pattern of the computer central processing unit, also known as RISC (abbreviation of Reduced Instruction Set Computer).This design idea simplifies the number of instructions and addressing methods, making it easier to implement, better in parallel execution of instructions, and higher in efficiency of the compiler.Commonly used reduced instruction set microprocessors include DEC Alpha, ARC, ARM, AVR, MIPS, PA-RI***ower Architecture (including PowerPC) and SPARC.

The origin of this design idea was the discovery that although traditional processors have many features designed to make code writing easier, these complex features require several instruction cycles to implement and are often not used by running programs.

In addition, the difference in operating speed between processors and main memory has become larger and larger.Driven by these factors, a series of new technologies have emerged, which enable the processor's instructions to be executed in a pipeline, while reducing the number of times the processor accesses memory.In the early days, this instruction set was characterized by a small number of instructions, each instruction used a standard word length, short execution time, and the implementation details of the central processing unit were visible to the machine-level program.

RISC: Reduced Instruction Set Computer RISC is a microprocessor that executes fewer types of computer instructions.Originated from the MIPS mainframe (that is, RISC machine) in the 80s, the microprocessors used in RISC machines are collectively referred to as RISC processors.

This allows it to perform operations faster (more million instructions per second, or MIPS).Because computers require additional transistors and circuit elements to execute each instruction type, a larger computer instruction set makes the microprocessor more complex and slower to perform operations.

John Cocke of the IBM Research Center in Yorktown, New York, proved that about 20% of the instructions in a computer do 80% of the work. In 1974, he proposed the concept of RISC, which is used in many current microchips.

RISC: Reduced Instruction Set Computer (RISC: Reduced Instruction Set Computer) runs faster than CISC.

In 1981, the company ushered in a rare opportunity - John Country Broadcasting Corporation BBC intends to broadcast a program to improve the popularity of computers throughout the UK. They hope that Acorn can produce a matching computer, but Acorn lacks a suitable computer. chip.

ARM accounts for 32% of all 75-bit embedded processors, making it the most 32-bit architecture in the world. ARM processor is widely used in embedded system design, low power consumption and energy saving, very suitable for mobile communication field.

CISC (complex instruction set).Since the birth of the electronic computer, after decades of modification and replacement development, its instruction set has become larger and larger, and the design of the cpu has become more and more complicated in order to realize these instruction operations.

ARM is developed by a company called CPU (Cambridge Processor Unit). Its founders are an Austrian doctor of physics named Hermann Hauser and an engineer named Chris Curry.

After the establishment of the CPU company, it is mainly engaged in the business of designing and manufacturing electronic equipment. In 1979, the company changed its name to Acorn Computer Ltd.

Consumer electronics, such as portable devices (PDAs, mobile phones, multimedia players, handheld video games, and computers), computer peripherals (hard drives, desktop routers), and even military equipment such as onboard computers for missiles .

However, statistical data shows that most of the calculations that occupy CPU and other computer resources are commonly used simple instructions in the small part of the instruction set, and the probability of actually using the remaining complex instructions that account for the vast majority is very small. It also caused the low utilization rate of the complex structure designed for it in the cpu.

At present, the CPU of this instruction system is generally used in middle and high-end servers, especially the high-end servers all use the CPU of the RISC instruction system.The CPUs that use RISC instructions in mid-to-high-end servers mainly include Alpha from Compaq (Compaq, namely the new Hewlett-Packard), PA-RISC from HP, Power PC from IBM, MIPS from MIPS, and Sparc from SUN.

The number of devices equipped with ARM chip architecture is 25 times that of Intel.99% of the world's smartphones and tablets use the ARM architecture.About 43 billion people touch a device equipped with an ARM chip every day, accounting for 60% of the world's total population.

Faced with this situation, computer experts began to study the necessary simplification of the instruction set, so that each instruction can be simplified and normalized, and a series of continuous, simple, densely encoded instructions can be executed to realize complex computer operations. , so as to replace those complex instructions that are rarely used in the instruction set to simplify the design complexity of the processor.

RISC and CISC are CPUs that can be divided into two categories from the characteristics of the instruction set: CISC and RISC. CISC is the abbreviation of Complex Instruction Set Computer, referring to "complex instruction set".

Professor Yao Zhaoming participated in the development of RCA70, known as the originator of RISC processors, at RCA Corporation in the United States before returning to teach at Xiangjiang University in the early 1802s. He is no stranger to the concept of RISC (Reduced Instruction Set) proposed in recent years.

The instruction set architecture that Bai Zirui was most familiar with in his previous life was the ARM architecture, which is one of the most popular RISC architectures in the 21st century. ARM is a RISC processor architecture and related technology introduced by Advanced RISC Machines Limited.

The instruction system of RISC is relatively simple. It only requires the hardware to execute the very limited and most commonly used instructions. Most complex operations are synthesized from simple instructions using mature compilation technology.

At that time, the price of 16-bit chips of National Semiconductor and Motorola was too high, and at the same time, Intel (Intel), which was in full swing, refused to provide them with design materials and samples of related processors (80286).After being rejected by Intel, Acorn decided to develop a new low-cost processor chip by itself.

Acorn's R&D staff found a research on a new type of processor from the beautiful country of University of California, Berkeley - a simplified instruction set, which just met their design requirements.

On this basis, after years of hard work, computer scientists Sophie Wilson and Steve Furber from the University of Cambridge finally completed the design of the microprocessor. Acorn named the chip Acorn RISC Machine, which is the famous "ARM" The origin of the three letters.

The model of the first processor chip developed by Acorn in 1985 was designated as ARM1. ARM1 and Intel's 80286 processors at the same time have their own strengths.

The structure of ARM1 is very simple, with only 25 transistors. In the second year, the improved version of ARM000 was released. ARM2 has a 2-bit data bus, 32-bit addressing space, and provides an addressing range of 26 Mbyte and 64 16-bit scratchpad.