Input. Process. Store, output

There are four steps that any computer uses in doing its Job. These are (1) inputting of data into the computer, (2) processing of the data that has been input, (3) storage of data, and (4) pro­duction of some kind of useful output.

In business computers, this four-step process is very easy to see. In order to produce a bill for a customer, we would have to input the information about what the customer bought. Once all of this information had been input, the computer would process this information and would print the information for the customer's bill. Throughout this cycle, the computer would be storing (t) the data that had been input, (2) the data produced during intermediate processing steps, and (3) the data being printed out. Apart from processing data, computer systems are being increasingly used to store data; such storage has the advantage of allowing data to be rapidly retrieved.'

In manufacturing, computers are used to control robots. If you think about it, any robot has to use some sort of a computer as the basis for its "intelligence". If we were to build a robot to be used in the assembling of automobiles, and if our robot had the specific task of mounting wheels on the car, the instructions for this process would be input into the computer. In addition,² the robot would still have to be able to determine where the car and the wheel were. Various types of sensors, such as a television camera, would enable the robot to "see" the position of the wheel and the car. In this case, we would not have to type information into a computer for the robot to act.³ We do have to have some means of getting the data into the computer, like a television camera. If we were to build this robot correctly, it would use the television camera to tell where the car was, where the wheel was, and even where the lug nuts⁴ were. The television camera would be the input. The process would be the calculations required to determine how to get the wheel on the car, and the output would be the robot's response to these calculations: mounting the wheel on the car, putting on and then tightening the lug nuts, and checking to see if the tire were properly mounted. The basic steps — input, store, process, and output — would be taking place with our robot even though no data was typed into the robot's computer (remember that the instructions had been input earlier, and were

' such storage has the advantage of allowing data to be rapidly retrieved —

преимуществом такого накопителя является возможность быстрого извлечения

данных

² in addition — вдобавок (к этому) '' for the robot to act —чтобы привести робота в действие ⁴ tug nut—барашковая гайка

being stored). The sequence of input, store, process, output takes place no matter what kin^ of computer we use. Let's take one more

case.

In medicine, doctors and technicians use computers in X-ray devices called CAT (Computerized Axial Tomography) scanners. This machine enables a doctor to see representations of the tissue inside a person's body without having to cut into the body. These devices use X-rays to take not just one still picture (what we know as the standard X-ray) but a series of pictures, much the same as' the series of still frames of a motion picture. In addition, CAT scanners have the ability to give the picture a three-dimensional quality.² That is, once the series of X-rays has been taken,³ the CAT scanner can do the required calculations to display a picture that is a composite of many other pictures. The doctor can tell the computer that he wants to view an organ or piece of tissue from any angle. The computer allows the doctor to look at the picture from that angle and in three dimensions.

Complicated as this may sound,⁴ the same basic steps of input, store, process, and output take ptace. Two inputs are required:

the first is the required series of X-rays; the second is the set of instructions from the doctor telling what he wants to see- As the X-rays are taken, the information about them is stored by the computer system for further use. Once the computer has the desired input, it will process the stored information and produce its output (a picture of what the doctor requested), which can also be stored by the computer to be used in the future if necessary.

Let us continue to examine this process of input, store, process, and output. One of the more common ways to input data into the computer is through the use of the computer keyboard.

Computer Keyboard

The computer keyboard is fashioned after⁵ a normal typewriter keyboard. The major difference is that a computer keyboard has more keys than a typewriter. These extra keys can send special characters to the computer. Each different model of computer responds to each of these special keys differently. Computer keyboards manufactured by different companies have these special keys in different places. Consult your instruction book, for the correct use of these special keys.

^ much the same as — почти таких же, как з ^а ^'"^-dimensional quality—объемное изображение

°"fe the series of X-rays has been taken — когда серия рентгеновских снимков отснята

а . """Pirated as this may sound — Хоть все это и звучит замысловато

^ls lashioned after — построена по образцу У-

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Pi^uiv G, The computer keyboard

The position of the keys for the tetters and numbers is the same on both typewriters and computer keyboards. The difference between the two is that the computer keyboard has additional punctuation and special computer control keys.

Most noticeable is the addition of the escape key" (sometimes called the altmode key"), the break key,'² (sometimes called the interrupt key¹²), and the control key.'³ Computer keyboards also have a shift key which functions the same as a shift key on a regular typewriter.

Most of the keys behave exactly like the keys on an ordinary

' RPT -- повтор

² ESC — переход

³ BACK SPACE—удаление символа слева от курсора

⁴ DEL—удаление символа справа от курсора

⁵ CTL -- управление

⁶ CAP LOCK— фиксированный верхний рггиетр

⁷ RETURN возврат

⁶ SHIFT—перевод регистра

'' ENT — ввод

'"SPACE ВАК—клавиша пробела

^п escape key=attmode key—клавиша перехода

¹² break key = interrupt key—клавиша прерывания

¹³ control key—клавиша управления

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typewriter: when you press the key, something happens immediately. But there are three keys on a computer keyboard that behave dif­ferently in that, when you press them, nothing seems to happen. These three keys are the shift key, the control key, and quite often the escape or altmode key.

The shift key and the control key modify the actions of any other key that is pressed at the same time as either of the first two. Sometimes the escape or altmode key will modify the actions of the next few keys pressed after the escape or the altmode key. For example, escape sequences (the pressing of a sequence of keys beginning with the escape key) are often used to clear the screen on a video terminal or to cause words to be highlighted. Usually the computer's instruction book will fully describe the effect of pressing the control or escape keys.

We have stated how to input data into the computer using a keyboard. But what kind of data should be typed?

Instructions to type

One of the types of data that is input using a computer key­board is instructions to the computer. If we had a business compu­ter to which we wanted to give instructions to start processing the payroll,' we would have to type in² the instruction to "Run payroll" or simply "payroll".

In fact, it may not be as simple as typing "payroll" because there are many steps to the operation of calculating somebody's payroll and having it printed out. Part of a payroll system³ is the program necessary to input an employee's name and address, Social Security⁴ number, marital status,⁵ number of deductions⁶ and all the necessary information about the employee.

Computer Output

In addition to accepting all of this information, all this input needed for the computer to do its required processing, we must determine exactly what kind of output we need from the computer. In the case of a payroll system, the two most important outputs are a paycheck for each employee and. for management, a totalling of what payroll costs were for this payroll period.

processing the payroll—заполнение платежной ведомости to type in - - ввести с клавиатуры payroll system — расчетная система bocial Security—социальное страхование-marital status — семейное положение

"umber of deductions— количество удержаний (из заработной платы) Walling of what payroll costs were — какова была общая сумма выплат по платежным ведомЬстям

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When a company bookkeeper sits down at a business computer, he has his choice of telling the computer that he wants to input .or retrieve information about payroll, inventory, accounts re­ceivable.' or accounts payable² Remembering all of these commands and all of the possible choices is sometimes a bit confusing.

Menu System³

To help a person control the bookkeeping system by computer, the computer can be programmed with what is known as a menu system. This menu system for a program or' for data selection enables the person running the computer to see a list of the things he can do next. Each item on the menu can, if necessary, select its own menu; and that menu can, in turn,⁴ call still other menus. For example, the person who is trying to manage a company's accounting system may sit down at the business computer and be shown a menu that would let him select accounts payable, accounts receivable, general ledger, inventory, or payroll. The computer operator might then select payroll, whereupon the computer would then respond with the payroll menu, showing items necessary to guide the computer operator. One such item might be "enter hours worked". Selecting this item would allow the computer operator to input to the computer the number of hours that each employee had worked during the pay period.

Another item might be "print paychecks". Once all of the in­formation had been input and the computer operator was satisfied that the information was correct, the computer could be directed to actually print the employee paychecks.