計算機的基礎部件

The Basic Components of Computers

1 ．The System Unit

　　The system unit is the core of your computer. It's inside the system unit that data is processed and stored.
　　The heart of the system unit is the CPU．The fact that your computer can run DOS means that the CPU in your computer belongs to the 8086 family of processors．This family includes the original 8086 as well as the 8088，the 80186，the 80286, the 80386，and the80486.
　　Although each of these processors has different capabilities, they can all run DOS．The CPU is the part of your computer that actually does the computing. Although the CPU performs manipulations on data. It can only hold data that it is currently working on. Most of the information in a computer is stored in the computer's main memory until TheCPU needs it. Memory is often called RAM, an acronym for Random Aclearcase/" target="_blank" >ccess Memory.
　　Basically, two things are stored in RAM：data and programs．When a program is executing, it re-sides in RAM, along with the data needed by the pro-gram.

2. Keyboards and Mouse

　　The basic input device on most microcomputer systems is a keyboard. Through the keyboard you “talk" to a computer. That is, it allows you to input information, instructions，or data to the computer.
　　Keyboards vary considerably from system to system, but most look a lot like a standard typewriter keyboard. Many also have a numeric keypad on the Right, which looks like the keypad on a 10-key adding machine. The keypad makes it easy to input large amounts of numerical data into the computer.
　　Computer keyboards usually have a number off unction keys．When pressed, a function key causes a particular action in the computer. For example, one key may tell the computer to clear the video screen of any information displayed, and another may tell the computer to send the information displayed on the screen to the printer so that a permanent copy can be obtained. Function keys are handy and convenient, since they allow you to “tell” the computer to do something by simply pressing one key！Keyboards without function keys often require you to press several keys in succession in order to give the computer one instruction.
　　Another common device is the mouse．You operate the mouse by moving it around the surface of your desk. As you move it, a special cursor called the mouse pointer moves around the screen in the same direction as you move the mouse. Programs that sup-port a mouse use the buttons on the mouse to select various options.

3 ．Monitor

　　Video displays vary considerably in style and options．Some display in black and white；Others are amore eye pleasing green; and some can display in color. Many can display only standard upper and lower case letter, numbers and punctuation marks on the screen.
　　Better display can show text material in several intensities．For example, you may see a frequently used business form with the printed material appearing on the screen in a light or half intensity, while the instructions on how to fill it out are in bold or double intensity, and the information you type in may appear on the screen in standard intensity. Displays vary in terms of capacity as well．Some are able to display no more than 12 lines at once, with30 or 40 characters in each line. Most computers can show 24 or 25 lines with up to 80 characters in each. Like most things in life, the displays with more features generally cost more.

4. Floppy Disk and Fix Disk

　　There are two basic “flavors” of floppy drives：The 5.25-inch mini floppy and the 3.5-inch microfloppy.
　　As you can see in the Figure 1-4, both types of floppy disks have a write-protect notch. For the 5.25 inch floppy，when the write -protect notch is uncovered. The disk drive write data to the disk. When the notch is covered (using an adhesive strip usually sup-plied with the diskette), the drive can read from the disk but not write to it: for the 3.5 inch floppies, the mechanics are reversed. When the write-protect notch of a 3.5 inch diskette is covered，the disk can be writ-ten to. When the notch is uncovered，the disk cannot be written to. Unlike the mini floppy, to write-protect a microfloppy, you simply move a built in slider; no adhesive strip is required. In either case, when a disk cannot be written to, it is write-protected.

　　The magnetic medium that actually holds the information should be considered quite fragile. In the case of a minifloppy, a small portion of the medium is always exposed because the read-Native opening is uncovered. In the case of a microfloppy, the shutter protects the medium when the diskette is not in use. When a microfloppy is inserted into the disk drive, the shutter is opened automatically when the diskette is accessed. Because the magnetic medium is fragile and susceptible to contamination by dust or smoke and erasure by magnetic fields, above all else, remember this basic rule about diskettes：If the medium is dam-aged, it will be impossible to retrieve any information stored on that diskette.
　　Most likely, your computer contains at least one fixed disk. Fixed disks are also referred to as hard disks because their magnetic medium is rigid. As stated, the magnetic medium of a fixed disk is not removable. Your computer probably contains a fixed disk for two reasons：it is much faster at reading and writing information than a floppy drive and it can hold far more information. Fixed disks can hold any wherefrom 10 million to 1000 million bytes of information. In computers, the prefix mega (sometimes abbreviated) denotes 1 million. Therefore, if someone says that you have a 80 megabyte drive, this means it can hold about 80 million bytes of information．
    One thing to remember about the fixed disk is that it is the most fragile component in your system. A severe shock can damage it. Therefore, make sure your system is located in a place that is free from excessive vibration.

5. Printer
　　Most microcomputer printers print one character at a time, usually at rates varying from 30 to perhaps180 characters per second. A more reasonable approach is to use a line printer, which, as the name implies, prints line by line instead of character by character. Rates of 1000 lines per minute (and more) are common. Even greater speed can be obtained by using a page printer to churn out complete pages at a time.

翻譯：

計算機的基本部件

1.系統部件
   
　　系統部件是你計算機的核心。數據正是在系統部件內被處理和存儲的。
    系統部件的核心是CPU.你的計算機能運行DOS這個事實表明你的計算機中的CPU屬于8086處理機系統。這個系統包括最早的8086和8088，80186，80286，80386和804860盡管這些處理機各有不同的能力，它們卻能運行DOS. CPU正是你的計算機中實際進行計算的音區件。
　　雖然CPU能對數據進行操作，但是它只能保存當前正在處理的數據。大多數計算機中的信息存儲在計算機的內存中，直到CPU需要使用它們。存儲器也常稱為RAM是隨機存取存儲器的縮略詞。
    基本上，在RAM中存儲了兩樣東西：程序和數據。當一個程序執行時，它駐留在RAM中連同這個程序所需要的數據一道。

2.鍵盤與鼠標

    大多數微型計算機的輸入設備是鍵盤。你是通過鍵盤與計算機“對話”的。也就是說：它允許你將信息、指令或數據輸入計算機。
    計算機系統不同，鍵盤也會很不相同。但大多數鍵盤的外型與標準打字機鍵盤相似。許多鍵盤的右邊還有一套數值鍵，它們看起來就像10鍵加法器上的小鍵盤。這種數值鍵使計算機可方便地進行大量數據錄入。
　　計算機鍵盤上通常還有一些功能鍵。當按下功能鍵時，可在計算機上產生一個特殊的操作。例如， 一個鍵可以告訴計算機清除當前顯示在屏幕上的任何信息，另一個鍵也許是告訴計算機將顯示在屏幕上的信息打印出來功能鍵是非常方便的，因為通過它們簡單地按一個鍵，便能讓計算機完成相應工作。假如沒有功能鍵．通常需要你同時連續地按幾個鍵萬能給計算機發出一條指令。
    另一種普通類型設備是鼠標你把鼠標放在桌面上移動便可操縱它。你在移動它時，一個叫做鼠標指針的特殊光標沿著你移動鼠標的方向在屏幕上移動。支持鼠標的程序使用了鼠標上的按鍵來做各種選擇。

3.顯示器
 
　　顯示器在式樣、性能和配置上有許多種規格。有些顯示器是黑白的；有些是使眼睛起來較舒服（不易疲勞）的綠色：有些能夠顯示彩色。多數顯示器只能顯示標準的大小寫字母、數字和標點符號。
　　好的顯示器能顯示好幾種亮度的文本。例如，你可以看到常用商業報表的表格線是以淺色或半亮度的色調顯示在屏幕上，而表格中的文字信息則是以粗的或倍亮度的色調顯示在屏幕上，你所鍵入的字符也許是以標準色調顯示在屏幕上。
　　顯示器在性能上有所不同。有些顯示器只能顯示12行，每行30至40個字符。大多數計算機能夠顯示24或25行，每行達80個字符。正如日常生活中的大多數事情一樣，顯示器性能愈好，其價格也就愈貴。

4.軟盤與硬盤

　　有兩種基本格調的軟驅：使用5.25英寸的小型軟盤驅動器和3.5英寸的微型軟盤驅動器。
　　正如你在圖1-4中所見，兩種類型的軟盤都有一個寫保護槽。對5.25英寸軟盤來說，當寫保護槽是打開的時候，磁盤驅動器能向磁盤上寫數據。當槽口被遮住時（常用隨磁盤提供的不于膠軟條），驅動器可從磁盤上讀取信息但不能寫信息到磁盤上；而對3.5英寸的軟盤情況則相反，當3.5英寸軟盤的寫保護槽被遮住時，能向磁盤上寫信息，當槽口敞開時，則不能往盤上寫信息。不像小型軟盤那樣，為微軟盤加寫保護，只需移動盤內固有的滑片即可，不需要使用不干膠軟條。無論在哪種情況下，當不能往磁盤上寫信息時，磁盤處寫保護狀態。
　　應該知道，實際存儲信息！性媒體是很易被損壞的。就小盤而言，因為讀寫孔是敞開的以媒體的一小部分總是暴露在就微軟盤而言，當軟盤不用時，遮板保護著媒體。把一片微軟盤插進磁盤驅動器中，當對磁盤進行訪問時，遮板自動地被打開。由于磁性媒體是易受損的，而且對灰塵或煙霧的污染和對磁場的消除信息極為敏感最重要的是，記住這個關于磁盤的基本原則：如果媒體受到損害，就不可能檢索出存儲在磁盤上的任何信息了。
　　多數情況下，計算機至少含有一個硬盤固定盤也被稱為硬盤，因為它們的磁性媒體是硬性的。正如所述的，硬盤的磁性媒體是不可移動的飛你的計算機可能含有一個硬盤是基于這兩個原因：它讀寫信息的速度遠比軟盤快得多，而且它能存儲多得多的信息。硬盤在任何地方都可存儲10兆到1000兆字節的信息在計算機領域，前綴mega（有時縮寫為M）表示1兆。所以，如果說你有80兆字節的驅動器，這意味著它能存儲約80兆字節信息。
　　關于硬盤應記住的一件事是：它是你的系統中最脆弱的部件，劇烈的震動就會損壞它。所以，要確保你的系統被放置在一個無過分振動的地方。

5.打印機

    大多數微型機上的打印機一次打印一個字符，其打印速度大致在每秒30至180個字符之間。比較合理的方案是采用行式打印機輸出。顧名思義，所謂行式打印機就是一行一行的，而不是一個字符一個字符地打印輸出。它們通常的打印速度是每分鐘1000行以上；若使用每次打印輸出一頁的頁式打印機我們還可以獲得更快的打印速度。

原文轉自：http://www.kjueaiud.com