A certain microcomputer is installed with a 64-bit operating system. What does 64-bit mean?

A certain microcomputer is installed with a 64-bit operating system. 64-bit refers to the word length of the CPU, that is, the CPU can process 64-bit binary data at a time. The word length is one of the main technical indicators of the CPU. It refers to the number of binary digits that the CPU can process in parallel at one time. The word length is always an integer multiple of 8. Usually the word length of a PC is 32 bits or 64 bits.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

A certain microcomputer is installed with a 64-bit operating system. 64-bit refers to the word length of the CPU, that is, the CPU can process 64-bit binary data at a time.

Computers use binary encoding to represent numbers, characters, instructions and other control information. When a computer is storing, transmitting or operating, a set of binary codes as a unit is called a word, and the number of binary bits in a word is called the word length.

The word length is one of the main technical indicators of the CPU. It refers to the number of binary digits that the CPU can process in parallel at one time. The word length is always an integer multiple of 8. Usually the word length of the PC is 32 bits, 64 Bit.

64-bit CPU processes binary data with a word length of 64 bits at the same time. Each binary 0 or 1 is the smallest unit that makes up the binary system, called a bit. Commonly used word lengths are 8 bits, 16 bits, 32 bits and 64 bits. An 8-bit encoding is called a byte, which is the basic encoding unit in computers.

A 64-bit CPU may have an external data bus or an address bus of different sizes inside, which may be larger or smaller; the term "64-bit" is also often used to describe the size of these buses. For example, many machines today have 32-bit processors (such as the original Pentium and later CPUs) that use a 64-bit bus, and are therefore sometimes referred to as "64-bit". Similarly, some 16-bit processors (such as the MC68000, a 16-bit processor produced by Motorola, named after integrating approximately 68,000 transistors) refer to 16/32-bit processors with a 16-bit bus, but There's some 32-bit performance under the hood too. The term may also refer to the instruction length of a computer's instruction set, or to other data items (such as common 64-bit double-precision floating point numbers). Without further qualifications, a "64-bit" computer architecture typically has 64-bit wide integer registers that can support (both internally and externally) 64-bit "chunks" of integer data.

Comparison of 64-bit and 32-bit

The change from 32-bit to 64-bit architecture is a fundamental change, because most operating systems must be completely modified, to gain the advantages of the new architecture. Other software must also be ported to take advantage of the new capabilities; older software is typically supported through hardware compatibility mode (new processors support older 32-bit versions of the instruction set) or software emulation. Or implement a 32-bit processor core directly in a 64-bit processor (like Intel's Itanium processor, which contains an x86 processor core to execute 32-bit x86 applications). Operating systems that support 64-bit architecture generally support both 32-bit and 64-bit applications.

The obvious exception is the AS/400, whose software executes on a virtual instruction set architecture called TIMI (Technology Independent Machine Interface), which converts low-level software into native machine code before execution. Low-level software must be completely rewritten to move the entire OS and all software to the new platform. For example, when IBM moved the older 32/48-bit "IMPI" instruction set to 64-bit PowerPC (IMPI is not at all like 32-bit PowerPC, so it's much better than moving from a 32-bit version of the instruction set to a 64-bit version of the same instruction set The scale is even larger).

The 64-bit architecture can undoubtedly be used in applications that need to process large amounts of data, such as digital video, scientific computing, and early large databases. There has been much debate over whether its 32-bit compatibility mode will be faster than equivalent 32-bit systems in other tasks. In x86-64 architecture (AMD64 and Intel 64), major 32-bit operating systems and applications can run smoothly on 64-bit hardware.

Sun's 64-bit Java virtual machine starts slower than 32-bit virtual machines because Sun still assumes that all 64-bit machines are servers and only implements "server" compilers for 64-bit platforms (C2). The "client" compiler (C1) produces slower code, but compiles faster. So although a Java program on a 64-bit JVM will perform better over a long period of time (typically long-running "server" applications), its startup time may be longer. For short-lived applications (such as the Java compiler javac), increasing the startup time can control the execution time and make the 64-bit JVM slower overall.

It should be noted that speed is not the only consideration when it comes to 32-bit and 64-bit processors. Applications such as multitasking, stress testing, and clustering (for HPC) may be better suited for 64-bit architecture to be deployed correctly. For the above reasons, 64-bit clusters have been widely deployed in large organizations such as IBM, Vodafone, HP, Microsoft.

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