CHAPTER 2: HARDWARE
HARDWARE
Hardware includes the system unit, keyboard, mouse, monitor, and all the other interesting pieces of equipment that make up a computer system. Hardware includes the system unit, mouse, keyboard, monitor, and all the other interesting pieces of equipment that make up a computer system.
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| Hardware |
Topic 1: INSIDE THE CASE OR SYSTEM UNIT (PROCESSING AND MEMORY)
The system unit of a computer is sometimes thought of as a strange and the user does not have much understanding of what happens inside it. A metal case/box case with buttons and lights in the front and holes in the back is called the system unit. This is the most important part of a computer because it has the Central Processing Unit (CPU). The system unit performs calculations, and stores information.
To start, we discuss how a computer system represents data and program instructions.
DATA AND PROGRAM REPRESENTATION
In order to be understood by a computer, data and software programs need to be represented properly. Therefore, coding systems are used to represent data and programs in a way that can be understood by the computer.
Digital/Binary computers recognize only two states
OFF(0) and ON(1)
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| Two States (0 and 1) |
Bits and bytes, document size, storage capacity, and memory capacity are all measured in bytes.
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| Measurements |
Digital Data Representation
All computers today, such as the embedded computers, mobile devices, personal computers, supercomputers are digital computers. Most digital computers are binary computers, which can understand only two states and represented by the digits 0 and 1. All data processed by a binary computer must be in binary form (0s and 1s). A bit is the smallest unit of data. A bit, computing term derived from the phrase binary digit. Therefore, the inputs you enter via a keyboard, the software program you use to stored data on your computer are all just groups of bits. Representing data in a form that can be understood by a digital computer is called digital data representation. Because most of computers can only understand data and instructions in the binary form, we can say that binary is the computer’s natural language.
You do not speak in binary. For example, you are not likely to go up to a friend and say,
0100100001001001
Which translates into the word “HI” using one binary coding system?
Representing Numerical Data: The Binary Numbering System
The numbering system we commonly use is called the decimal numbering system because it uses 10 symbols, the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9, to represent all possible numbers. Numbers greater than nine, such as 21 and 683, are represented using combinations of these 10 symbols. The binary numbering system uses only two symbols, the digits 0 and 1, to represent all possible numbers.
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| Decimal Numbers System |
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| Binary Numbers System |
Coding Systems for Text-Based Data
Text-based data is represented by binary coding systems specifically developed for text-based data called ASCII (American Standard Code for Information Interchange). ASCII is a fixed-length, binary coding system used to represent text-based data for computer processing on computers. These codes are used to represent all characters that can appear in text data, such as letters, numbers, and special characters like the dollar sign, comma, percent symbol.
Graphics Data
Graphics data consists of still images, such as pictures or drawings. One of the most common methods for storing graphics data is in the form of a bitmap image, an image comprised of a grid of small dots, called pixels (short for picture elements).
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| Pixels (Picture Elements) |
256-COLOR IMAGE The color of each pixel is represented using one byte (8 bits).
Audio Data
Like graphics data, audio data, such as music must be in digital form in order to be stored on a storage medium. The actual storage size required depends on the bit rate, the number of bits to be transferred per second when the file is played. Audio files using the common bit rate of 128 Kbps (thousands of bits per second).
Video Data
Video data such as movies, video clips is displayed using a collection of frames; each frame contains a still image. When the frames are projected one after the other (typically at a rate of 24 frames per second), the illusion of movement is created.
Machine Language
As numbers and text must be represented by 0s and 1s, software programs must also be represented by 0s and 1s. Before a computer can execute any program instruction, such as moving a file from one storage device to another, or opening a new window on the screen, it must convert the instruction into a binary code known as machine language. An example of a typical machine language instruction is as follows:
01011000011100000000000100000010
A machine language instruction might look like a meaningless string of 0s and 1s, but it actually represents specific operations and storage locations.
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