计算机专业英语 学习笔记 1

Principlesof computer organization>

Computerhardware> We build computers to solve problems. Early computers solvedmathematical and engineering problems, and later computers emphasizedinformation processing for business applications. Today, computers also controlmachines as diverse as automobile engines, robots, and microwave ovens. Acomputer system solves a problem from any of these domains by accepting input,processing it, and producing output.

Computersystems consist of hardware and software. Hardware is the physical part of thesystem. Once designed, hardware is difficult and expensive to change. Softwareis the set of programs that instruct the hardware and is easier to modify thanhardware. Computers are valuable because they are general-purpose machines thatcan solve many different kinds of problems, as opposed to special-purposemachines that can each solve only one kind of problems. Different problems canbe solved with the same hardware by supplying the system with a different setof instructions, that is, with different software.

Everycomputer has four basic hardware components: input devices, output devices,main memory, central processing unit.

Fig. 1-2shows these components in a block diagram. The lines between the blocksrepresent the flow of information from one component to another on the bus,which is simply a group of wires connecting the components. Processing occursin the CPU and main memory. The organization in Fig. 1-2, with the componentsconnected to each other by the bus, is common. However, other configurationsare possible as well.

Computerhardware is often classified by its relative physical size: smallmicrocomputer, medium minicomputer, large mainframe. Just the CPU of amainframe often occupies an entire cabinet. Its input/output devices and memorymight fill an entire room. Microcomputers can be small enough to fit on a deskor in a briefcase. As technology advances, the processing capabilitiespreviously possible only on large machines become possible on smaller machines.Microcomputers now can do much of the work that only minicomputers ormainframes could do in the past.

Theclassification just described is based on physical size as opposed to storagesize. A computer system user is generally more concerned with storage size,because that is a more direct indication of the amount of useful work that thehardware can perform. Speed of computation is another characteristic that isimportant to users. Generally speaking, users want a fast CPU and largecapacity of storage, but physically small I/O devices and main memory.

Whencomputer scientists study problems, therefore, they are concerned with spaceand time – the space necessary inside a computer system to store a problem andthe time required to solve it. They commonly use the metric prefixes of Table1-1 to express large or small quantities of space or time.

Prefixgiga-(G) mega-(M) kilo-(K) milli-(m) micro-(u) nano-(n)

Supposeit takes 4.5 microseconds, also written 4.5 us, to transfer some informationacross the bus from one component to another. How many seconds are required forthe transfer? How many transfers can take place during one minute?

Notethat since the original value was given with two significant(有效的) figures, the result should notbe given to more than two or three significant figures.

Asopposed to metric system, in computer science the different between 1000 and1024 is less than 3%, so you can think of a computer science kilo- as beingabout 1000 even though it is a little more. The same applies to mega- andgiga-, as in Table 1-2. This time, the approximation is a little worse, but formega- it is still within 5%.

Inputdevice 输入设备information processing 信息处理 output device 输出设备

Hardware硬件 main memory主存 software 软件 central processing unit 中央处理器

Program 程序 bus 总线 general-purpose machine 通用计算机 microcomputer 微型计算机

Special-purposemachine 专用计算机 minicomputer小型计算机instruction 指令

Mainframe大型机 set ofinstructions 指令集

When westore a problem into a computer, space and input device is necessary.

Early computersolved engineering and mathematical problems.

We canuse prefix micro to express time metric and 10^(-6)

We cansay a bus is simply a group of wires, a 8-bit bus, a 16-bit bus.

Acomputer system user generally more cares for storage size, speed ofcomputation, efficiency of the computer.

Accordingto the physical size of computers we can classify the computers intomicrocomputer, minicomputer, mainframe, supercomputer.

Prefix megaused for computer science is larger than 10^6, equal to 2^10.

Thebasic hardware components of any computer include CPU, main memory, inputdevices, output devices.

Fill inthe blank with appropriate words or phrases found behind this exercise.

A computersystem solves a problem by accepting input, processing problem, and producingoutput.

The amountof effective work of a computer can be indicated by storage size directly.

Computersystems consist of hardware and software.

Computerthat can solve only one kind of problem is a special-purpose machine.

Computerthat can solve many different kinds of problems is a general-purpose machine.

Softwareinstructs the hardware.

Hardwareis difficult and expensive to change.

We usuallyshow the computer components in a block diagram.