速求 一篇关于计算机发展历史和特点的大学英语作文 300字左右

速求 一篇关于计算机发展历史和特点的大学英语作文 300字左右
速求 一篇关于计算机发展历史和特点的大学英语作文 300字左右

速求 一篇关于计算机发展历史和特点的大学英语作文 300字左右
The oldest calculating tool is abacus that was invented by Chinese several thousand years ago. Since then human beings had tried to make a machine to calculate for many years. However, there had been no machine which can be called "computer" till 1946. In that year two Americans invented the first computer in the world. The volumn of the machine was so large that it took up a whole room, and its speed was very low. With the rapid development of IT, nowadays computers are much smaller and faster, and they have become one of essential tools for everybody.
MICROPROCESSOR AND MICROCOMPUTER
Microprocessor is a processor whose elements have been miniaturized into one or a few integrated circuits.It is a semiconductor central processing unit(CPU)and one of the principal components of the microcomputer.The elements of the microprocessor are frequently contained on a single chip or within the same package,but are sometimes distributed over several separate chips.[1] In a microcomputer with a fixed instruction set,the microprocessor consists of the arithmetic-logic unit and the control logic unit.In a microcomputer with a micro programmed instruction set,it contains an additional control-memory unit.[2]
Pentium And Power PC Evolution
In this section,we provide a brief overview of two computer families：the Intel Pentium and the IBM Power PC.The Pentium represents the results of decades of design effort on complex instruction set computers(CISCs).It incorporates the sophisticated design principles once found only on mainframes and supercomputers and serves as an excellent example of CISC design.The Power PC is a direct descendant of the first RISC system,the IBM 801,and is one of the most powerful and best-designed RISC-based systems on the market.[3]
1)The Pentium
One method of increasing the complexity of an integrated circuit is simply to scale the chip down.[4] For example,if every line etched into the silicon die could be shrunk in half,the same circuit could be built in one -fourth the area.The evolution of dynamic memory chips(DRAMs)follows this rule exactly.The original IBM PC used 16 KB DRAMs.These were soon replaced with 64 Kchips,then 256 KB chips,and now 16 MB,and even 64 MB chips…
The“trick”,of course,is being able to improve processing skills sufficiently to allow this scaling to continue.In 1969,the minimum feature size(the smallest detail that can be etched into a chip)was 10 microns(10×10-6 meter).By 1997,this had shrunk to 0.25 micron—40 times smaller!
The Pentium uses a superscalar architecture.This means that the chip’s capabilities go beyond those achieved simply by scaling down its size.In particular,the Pentium is the first microprocessor in the Intel family to support two instruction pipelines,each with its own arithmetic-logic unit,address generation circuitry,and data cache interface.The result is a processor that can actually execute two different instructions simultaneously.
In 1965,Gordon Moore,one of the founders of Intel,was graphing chip complexity vs. time. He noticed that the number of integrated components doubled every two years.Moore then boldly predicted that this doubling would continue indefinitely.Remarkab1y,his prediction—now referred to as Moore’s law—has held up for more than 30 years.[5]
2)The Pentium MMX
In 1996,Intel began delivering versions of the Pentium with multimedia extensions (MMXs).These processors have three architectural enhancements over non-MMX processors(now renamed Pentium Classic).
For general applications,benchmark tests show a 10一20 percent improvement over the Pentium Classic,increasing to nearly 70 percent when multimedia-specific plications are considered.[6] Chips with(internal)click speeds as high as 233 MHz are available.
Applications of MMX processors include decompression of audio and video files.Indeed,software video players may become a reality.Some vendors are replacing conventional modems and sound cards with MMX-driven software equivalents.
3)The Pentium Pro
Perhaps the most striking feature of the Pentium Pro is the package itself.As shown in Fig. 2-1 the Pro consists of two separate silicon dies.The largest is the processor;fabricated with 0.35 micron design rules,it incorporates 5.5 million transistors.The smaller die beside it is a 256 KB level-two cache.Oddly enough,the cache has three times as many transistor,as the processor(16.5 millions),but because of its uniformity,less silicon area is required.[7] Versions of the Pentium Pro with a 512KB,and a 1 MB cache are also available.
The Pentium Pro retains all of the architectural features of the Pentium that preceded it.That is,internally,all registers are 32 bits,while the external data bus is 64 bits wide.Four additional address lines have been added,allowing 64 GB of physical memory to be accessed.From a software point of view,the Pentium Pro remains 100% compatible with the previous generation of 80x86 processors.Three new processor instructions have been added,as well as two new floating-point-unit instructions.
The most touted feature of the Pentium Pro is what Intel calls dynamic execution.This new approach to processing software instructions that reduces idle processor time to an absolute minimum.
4)The Pentium II
The newest member of the 80x86 family is the Pentium II.First made available in 1997,it is basically a Pentium Pro with MMX technology.
The Pentium II is made with 0.25-micron technology,allowing clock speeds of 300 MHz to 450 MHz.System bus frequencies as high as 100 MHz are suonorted.The lower clock speeds will support a 66 MHz system bus frequency.The level-two cache,which operates at half the speed of the processor,stores 512 KB and has its own 64-bit dedicated bus.The level-one cache has been increased from 16 KB in the Pentium Pro to 32 KB in the Pentium II.
5)Power PC
In 1975,the 801 minicomputer project at IBM pioneered many of the architecture concepts used in RISC systems.T801,together with the Berkeley RISC I processor,launched the RISC movement.The 801,however,was simply a prototype intended to demonstrate design concepts. The success of the 801 project led IBM to develop a commercial RISC workstation product,the RT PC.The RT PC,introduced in 1986,adapted the architectural concepts of the 801 to an actual product.The RT PC was not a commercial success,and it had many rivals with comparable or better performance.In 1990,IBM produced a third system,which built on the lessons of the 801 and the RT PC.[8] The IBM RISC System /6000 was a RISC-like superscalar machine marketed as a high-performance workstation;shortly after its introduction,IBM began to refer to this as the Power architecture.
For its next step,IBM entered into an alliance with Motorola,developer of the 68000 series of microprocessors,and Apple,which used the Motorola chip in its Macintosh computers.The result is a series of machines that implement the Power PC architecture. Changes were made to add key missing features and to enable more efficient implementation by eliminating some instructions and relaxing the specification to eliminate some troublesome special case.[9] The resulting Power PC architecture is a superscalar RISC system.
So far,four member of the Power PC family have been introduced.
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