The function or performance of a computer is not determined by a certain index, but by its system structureCommand system, hardware composition, software configuration and other factors.
Computer and its related software and hardware equipment are the crystallization of modern science and technology.It is applied to industry, commerce, finance, education, scientific research, military, communication, national defense construction and other aspects of the national economy.The development of many industries increasingly shows strong dependence on computer science.So the evaluation and detection of computer is very important.The function or performance of a computer is not determined by a certain index, but by its system structure, instruction system, hardware composition, software configuration and other factors.For most ordinary users, you can generally evaluate the performance of the computer from the following indicators[1]。
Operation speed
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Operation speed is an important index to measure computer performance.Generally speaking, the computing speed (average computing speed) of the computer means that it can be executed every secondinstructionsThe number of instructions is generally described as "mips, Million Instruction Per Second".The time required to perform different operations on the same computer may be different, so different methods are often used to describe the operation speed.Common CPUclock frequency(main frequency), average number of instructions executed per second (ips), etc.MicrocomputerThe main frequency is generally used to describe the operation speed. For example, the main frequency of Pentium/133 is 133 MHz, the main frequency of Pentium III/800 is 800 MHz, and the main frequency of Pentium 4 1.5G is 1.5 GHz.Generally speaking, the higher the main frequency, the faster the operation speed[2]。
Word length
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A group of computers processed at the same timeBinaryThe number is called the "word" of a computer, and the number of bits of this group of binary numbers is the "word length".When other indicators are the same,Word lengthThe larger the computer, the faster it can process data.The word length of early microcomputers was generally 8 bits and 16 bits.586 (Pentium, Pentium Pro, Pentium II, Pentium III, Pentium 4) are mostly 32-bit, and most people install 64 bit[2]。
Memory capacity
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Memory, also referred to asMain storage, which can be directly accessed by the CPUstorageThe program to be executed and the data to be processed are stored in main memory.The size of the internal memory reflects the computer's ability to store information instantly.along withoperating systemThe upgrading of, the continuous enrichment of application software and the continuous expansion of its functionsComputer memoryThe demand for capacity is also increasing.functionWindows 95Or Windows 98 requires at least 16M of memory, and Windows XP requires more than 128M of memoryMemory capacity。The larger the memory capacity, the more powerful the system functions, and the larger the amount of data that can be processed[2]。
Capacity of external memory
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External memory capacity usually refers toHard diskCapacity (including internal hard disk and mobile hard disk).The larger the external memory capacity, the more information can be stored, and the applications that can be installedSoftwareThe more abundant.Hard disk capacity is generally 10G to 60G, and some even reach 120G[2]。
I/O speed
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The speed of host I/O depends onI/O busDesign.This does not matter much for slow speed devices (such as keyboards and printers), but it is very effective for high-speed devices.For example, for the currentHard diskIts external transmission rate has reached more than 20MB/S and 4OMB/S[2]。
Video memory
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The performance of video memory is determined by two factors:capacitySecondbandwidth。 The capacity determines how much data can be cached.In terms of bandwidth, it can be understood as the channel for video memory and core to exchange data. The larger the bandwidth, the faster the data exchange.So capacity and bandwidth are the key factors to measure the performance of video memory.In addition, bandwidth is determined by frequency and bit width. The calculation formula is: bandwidth=frequency X bit width/8.For example, for two video cards with the same core and video memory capacity, the video memory of card 1 is DDR3 1600MHz and 128 bit wide;The video memory of card 2 is DDR2 800MHZ frequency and 256 bit width.It seems that the video memory parameters of the two are different, but the formula shows that they both have 25.6G/S bandwidth and the performance is the same.Therefore, as long as we understand the essence, no matter how complex and changeable the product is, we cannot be fooled.
Video memory capacity: common capacities are 128M, 256M, 512M, 896M, 1G, etc.The larger the capacity, the more data can be cached.
Video memory frequency: There are DDR2, DDR3, GDDR3, GDDR5 and other types. GDDR5 has the highest frequency and its equivalent frequency can reach more than 4GHZ.DDR2 frequency is the slowest, some even only 667MHZ.
Video memory bit width: 64bit, 128bit, 256bit, 448bit, 512bit, etc.Bit widthThe greater the manufacturing difficulty, the higher the cost. Therefore, many manufacturers prefer to choose the combination of low bit width and high frequency to ensure the performance and reduce the cost (commonly used in A card products)[2]。
Hard disk speed
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Rotational Speed, YesHard diskThe rotation speed of the inner motor spindle is the maximum number of revolutions that the hard disk can complete in one minute.The speed of rotation is one of the important parameters to mark the grade of hard disk, and it is one of the key factors to determine the internal transmission rate of hard disk, which directly affects the speed of hard disk to a large extent.The faster the rotational speed of the hard disk, the faster the hard disk can search for filestransmission speed It has also been improved.The rotational speed of the hard disk is expressed in revolutions per minute (RPM). RPM is the abbreviation of Revolution Duration, which is revolutions per minute.The higher the RPM value, the faster the internal transmission rate, the shorter the access time, and the better the overall performance of the hard disk.The spindle motor of the hard disk drives the disc to rotate at a high speed, generating buoyancy to float the head above the disc.To bring the sector of data to be accessed below the head, the faster the speed is, the shorter the waiting time will be.Therefore, the rotational speed largely determines the speed of the hard disk[2]。
Dominant frequency
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CPUThe main frequency of the CPU coreclock frequency（CPU Clock Speed）。It is usually said that the number of megahertz of a certain CPU is "the main frequency of the CPU".Many people think that the main frequency of CPU is its running speed, but it is not.The main frequency of the CPU indicates the speed at which the digital pulse signal oscillates in the CPU, which has no direct relationship with the actual computing power of the CPU.becauseDominant frequencyIt does not directly represent the operation speed, so under certain circumstances, it is likely that the actual operation speed of CPU with higher dominant frequency will be lower.In electronic technology, a pulse signal is an analog signal that is sent out continuously at a certain voltage amplitude and time interval.Pulse signalThe time interval between is called period;The number of pulses generated in a unit time (such as 1 second) is called frequency.Frequency is a measurement name that describes the number of pulses that appear in the unit time of periodic cyclic signals (including pulse signals);The standard unit of measurement for frequency is Hz.The system clock in the computer is a typical frequency that is quite accurate and stablePulse signal generator。The frequency is represented by "f" in the mathematical expression, and its corresponding units are Hz, kHz, MHz and GHz.Where 1GHz=1000MHz, 1MHz=1000kHz, 1kHz=1000Hz.The time unit for calculating the pulse signal period and the corresponding conversion relationship are: s (seconds), ms (milliseconds), μ s (microseconds), ns (nanoseconds). The default main frequency of the AMD FX4170 CPU is 4.2G, which is the highest in history, including 1s=1000ms, 1 ms=1000 μ s, and 1 μ s=1000ns.The main frequency of the CPU, that is, the clock speed of the CPU core (CPU Clock Speed).What is the CPU of so and soMegahertzThe number of megahertz is the "main frequency of the CPU".There is a certain relationship between the main frequency and the actual operation speed, but there is no definite formula that can quantify the numerical relationship between the two, because the operation speed of the CPU also depends on various performance indicators of the CPU pipeline (cache, instruction set, CPU bits, etc.).Since the main frequency does not directly represent the operation speed, under certain circumstances, it is likely that the CPU with higher main frequency will have a lower actual operation speed.For example, most of AMD's AthlonFX series CPUs can achieve the CPU performance of Intel's Pentium 4 series CPUs with a lower dominant frequency, so the AthlonFX series CPUs are named by PR values.Therefore, the dominant frequency is only one aspect of CPU performance, not the overall performance of the CPU.
The dominant frequency of the CPU does not representCPUBut it is very important to improve the CPU operation speed by increasing the main frequency.For example, suppose a CPU is in aClock cycleIf an operation instruction is executed within, the CPU will run twice as fast when it runs on the 100MHz main frequency as when it runs on the 50MHz main frequency.Because the 100 MHz clock cycle occupies half the time of the 50 MHz clock cycle, that is, the time required for a CPU working on the 100 MHz main frequency to execute an operation instruction is only 10 ns, which is half shorter than the 20 ns working on the 50 MHz main frequency, and the natural operation speed is twice as fast.But the overall running speed of the computer depends not only on the CPU operation speed, but also on the operation of other subsystemsdata transmissionAfter the speed can be improved, the overall running speed of the computer can be really improved.
The improvement of CPU working frequency is mainly limited by the production process.Because the CPU issemiconductorIt is made on a silicon chip. The components on the silicon chip need wires for connection. The thinner and shorter wires are required in the high-frequency state, the betterwirewaydistributioncapacitanceAnd other stray interference to ensure correct CPU operation.Therefore, the limitation of manufacturing process isCPU main frequencyOne of the biggest obstacles to development.More mainstreamMemory frequency667MHz and 800MHzDDR2 memory, and 1333MHzDDR3 memory。The high-end ones are calculated in GHz, for example, the dominant frequency required by high-end enterprises is ≥ 2.4GHz.
The main frequency of processor has two concepts closely related to it:frequency doublingAndfsb , the external frequency is the reference frequency of the CPU, and the unit is also MHz.External frequency is the speed of synchronous operation between CPU and mainboard, and most of themcomputer system So are the intermediate and external frequenciesMemoryAnda main boardIn this way, it can be understood that the external frequency of the CPU is directly connected with the memory to realize the synchronous operation between the two;Frequency multiplication is the multiple of the ratio of main frequency to external frequency.Main frequency, external frequency and octave, the relationship is: main frequency=external frequency × octave.In the early days, CPU did not have the concept of "frequency multiplication". At that time, the speed of the main frequency and the system bus was the same.With the development of technology, the CPU speed is getting faster and faster, and the memory, hard disk and other accessories are gradually unable to keep up with the CPU speed. However, the emergence of frequency multiplication solves this problem. It can make the memory and other components still work at a relatively low system bus frequency, and the main frequency of the CPU can be infinitely improved by frequency multiplication (theoretically).We can regard the external frequency as a production line in the machine, and the frequency multiplication is the number of production lines. The speed of a machine's production (main frequency) is naturallyproduction lineThe speed (external frequency) of is multiplied by the number of production lines (frequency doubling).The manufacturers have basically locked up the frequency multiplication. The only way to overclock is to start from the external frequency. By matching the frequency multiplication with the external frequency, you can patch the motherboard or set a soft overclock in the BIOS, so as to improve the overall performance of the computer[2]。
