UNITS OF MEMORY

Bits - basic units of memory

Information is processed and stored in computer as electrical signals. A computer contains thousands of electronic circuits connected by switches that can only be in one of two possible states: ON (the current is flowing through the wire) or OFF (the current is not flowing through the wire).. To represent these two conditions we use binary notation in which 1 mean ON and 0 means OFF. This is the cnly way a computer can 'understand' anything. Everything about computers is based upon this binary process. Each 1 or 0 is called a binary digit or bit.

Bytes and characters

Is and Os are grouped into eight-digit codes that typically represent characters (letters, numbers and symbols). Eight bits together are called a byte. Thus, each character in a keyboard has its own arrangement of eight bits. For example: 01000001 for the letter A, 01000010 for В and 01000011 for С

The ASCII code

The majority of computers use a standard system for the binary representation of characters. This is the American Standard Code for Information Interchange, known popularly as 'ASCII 1 (pronounced 'ask-key'). There are 256 different ways of combining 0 and 1 bits in a byte. So they can give us 256 different signals. However, the ASCII code only uses 128 bytes to represent characters. The rest of the bytes are used for other purposes.

The first 32 codes are reserved for characters such as the Return key, Tab, Escape, etc. Each letter of the alphabet and many symbols (such as punctuation marks) as well as the ten numbers have ASCII representations. What makes this system powerful is that these codes are standard.

Kilobytes, megabytes and gigabytes

In order to avoid astronomical figures and sums in the calculation of bytes, we use units such as kilobytes, megabytes and gigabytes. One kilobyte is 1,024 bytes (210) and it is represented as KB. or more informally as K. One megabyte is equivalent to 1,024 KB, and one gigabyte is 1.024 MB.

We use these units (KB. MB, GB) to describe the RAM memory, the storage capacity of disks and the size of any application or document.

Make up your own topic using the following questions:

1. What are the basic units of memory?

2. What is bit?

3. What is a byte?

4. What does the ASCII code mean?

5. What are KB, MB, GB?

6. What units do we describe using KB, MB, GB?

Одиниці памті

Біти - основні одиниці пам'яті

Інформація обробляється і зберігається в комп'ютері у вигляді електричних сигналів. Комп'ютер містить тисячі електронних ланцюгів, підключених за допомогою перемикачів, які можуть знаходитися тільки в одному з двох можливих станів: ON (струм, що протікає через дріт) або OFF (струм не протікає через дріт) .. Для представлення цих двох умов ми використовуємо двійкова система числення, в якій 1 означає ON і OFF означає 0. Це cnly способом комп'ютер може "зрозуміти" що завгодно. Все про комп'ютерах засноване на цій бінарній процесу. Кожен 1 або 0 називається двійковий розряд або біт.

Байти і символи

Є і ОС згруповані у вісім-значні коди, які зазвичай представляють собою символи (букви, цифри й символи). Вісім бітів разом називають байта. Таким чином, кожен символ в клавіатура має своє власне розташування восьми бітів. Наприклад: 01000001 для літери А, для 01000010 для В 01000011 і для С

ASCII код

Більшість комп'ютерів використовує стандартну систему для двійковим поданням символів. Це Американський стандартний код для обміну інформацією, відомої в народі як 'ASCII 1 (вимовляється "АСК-ключ"). Є 256 різних способів поєднання 0 і 1 біт в байті. Так що вони можуть дати нам 256 різних сигналів. Тим не менш, код ASCII використовує тільки 128 байтів для представлення символів. Інша частина байта використовуються для інших цілей.

Перші 32 кодів зарезервовані для символів, таких як повернення ключ, Tab, втечу і т.д. Кожна буква алфавіту і багато символи (наприклад, знаки пунктуації), а також десять числа мають ASCII уявлень. Що робить цю систему потужним, що ці коди є стандартними.

Кілобайтах, мегабайтах і гігабайтах

Для того щоб уникнути астрономічних цифр і сум при розрахунку байт, ми використовуємо такі підрозділи, як кілобайти, мегабайти і гігабайти. Один кілобайт це 1024 байт (210), і вона представлена ​​у вигляді КБ. або більше неофіційно, як К. один мегабайт еквівалентно 1024 КБ, і одного гігабайта 1,024 Мб.

Ми використовуємо ці одиниці (KB. MB, GB) для опису пам'яті ОЗУ, ємність дисків і розмір будь-якої програми або документа.

Зробіть свою власну тему, використовуючи наступні питання:

1. Які основні одиниці пам'яті?

2. Що трохи?

3. Що таке байт?

4. Що означає ASCII код на увазі?

5. Які КБ, МБ, ГБ?

6. У яких одиницях ми описуємо використанням КБ, МБ, ГБ?

OUTPUT DEVICES

A. Point and click

Typically, a mouse is a palm-sized device, slightly smaller than a pack of cards. On top of the mouse there are one or more buttons for communicating with the computer. A 'tail' or wire extends from the mouse to a connection on the back of the computer.

The mouse is designed to slide around on your desktop. As it moves, it moves an image on the screen called a pointer or mouse cursor. The pointer usually looks like an arrow or I-bar and it mimics the movements of the mouse on your desktop.

What makes the mouse especially useful is that it is a very quick way to move around on a screen. Move the desktop mouse half an inch and the screen cursor will leap four inches. Making the same movements with the arrow key takes much longer. The mouse also issues instructions to the computer very quickly. Point to an available option with the cursor, click on the mouse, and the option has been chosen.

Mice are so widely used in graphics applications because they can do things that are difficult, if not impossible, to do with keyboard keys. For example, the way you move an image with a mouse is to put the pointer on the object you want to move, press the mouse button and drag the image from one place on the screen to another. When you have the image where you want it, you release the mouse button and the image slays there. Similarly, the mouse is used to grab one corner of the image (say a square) and stretch it into another shape (say a rectangle). Both of these actions are so much more difficult to perform with a keyboard that most graphics programs require a mouse.

The buttons on the mouse are used to select items at which the mouse points. You position the pointer on an object on the screen, for example, on a menu or a tool in a paint program, and then you press the mouse button to 'select' it. Mice are also used to load documents into a program: you put the pointer on the file name and double-click on the name - that is, you press a mouse button twice in rapid succession.

B. The monitor

The characters and pictures that we see on the screen are made up of dots, also called picture elements (pixels). The total number of pixels in which the display is divided both horizontally and vertically is known as the resolution. If the number of pixels is very large, we obtain a high resolution display and therefore a sharp image. If the number of pixels is small, a low resolution is produced. Typical resolutions are 640 x 480 or 1,024 X 768 pixels. Thus a larger number of pixels give a much clearer image.

The cathode ray tube of the monitor is very similar to that of a TV set. Inside the tube there is an electron beam which scans the screen and turns on or off the pixels that make up the image. The beam begins in the top left corner, and scans the screen from left to right in a continuous sequence, similar to the movement of our eyes when we read, but much faster. This sequence is repeated 50, 60 or 75 times per second depending on the system. If the rate of this repetition is low, we can perceive a flickering, unsteady screen, which can cause eye fatigue. However, a fast-moving 75 Hz 'refresh rate' eliminates this annoying flicker.

What we see on the screen is created and stored in an area of RAM, so that there is a memory cell allocated to each pixel. This type of display is called bit-mapped. On monochrome monitors, bits 0 are visualized as white dots, and bits 1 as black dots.

On colour displays, there are three electron guns at the back of the monitor's tube. Each electron gun shoots out a beam of electrons; there is one beam for each of the three primary colours: red, green and blue. These electrons strike the inside of the screen which is coated with substances called phosphors that glow when struck by electrons. Three different phosphor materials are used: one each for red, green and blue. To create different colours, the intensity of each of the three electron beams is varied.

The monitor is controlled by a separate circuit board, known as the display adaptor, which plugs into the motherboard of the computer. Different boards drive different types of displays. For example, the VGA (video graphics array) card has become a standard for colour monitors.

Portable computers use a flat Liquid-crystal display (LCD) instead of a picture tube. An LCD uses a grid of crystals and polarizing filters to show the image. The crystals block the light in different amounts to generate the dots in the image.

Make up your own topic using the following questions:

1. What is a mouse?

2. Why do we use a mouse?

3. What are the advantages of using a mouse to keyboard key?

4. How can a mouse make the work with graphic easier?

5. What are pixels?

6. What is resolution?

7. What is the cathode ray tube? How does it work?

8. What kind of monitors do you know?

9. What is an LCD? How does it work?