Computer Hardware Concepts
Computer hardware refers to the actual equipment, machines, and physical devices of a computer system. A typical personal computer system contains:
The system unit is the cabinet that contains the computer's working components. One of these components is the CPU or Central processing Unit. This is a very small electronic circuit chip. This device allows the computer to perform complex mathematical and logical functions. The CPU is identified by a name and number. For instance, an Intel Pentium III chip was designed by the Intel company. The Pentium III designation tells the user which version of the chip is in use.
Input devices allow the user to send information into the CPU. They may include the mouse, the keyboard or in some cases optical pens.
Output devices display the results of the computer programs and applications. A video monitor (looks like a TV screen) is often used on desktop models. Older monitors are quite bulky because they use a cathode ray tube to display information. Newer LCD displays are "flat screen" monitors. They use liquid crystal to display information and they are much more compact than earlier models. The colours that can be displayed on a monitor are various combinations of red, green and blue.
The mouse is used to move the cursor around on the screen. On the bottom of the mouse a small ball rolls around and this motion controls the signal that is sent to the computer. If your mouse does not respond quickly when you move it, then you may need to open it up and remove any dust or dirt.
An operating system is a set of programs that control the resources and components of the computer. It controls the BIOS (Basic Input and Output), allocates memory (RAM), and sychronizes hardware components such as the monitor, printer and disk drives. Modern operating systems include WIN 95, WIN 98, WIN 2000, WIN NT, Linux and MAC OS. An old operating system that is still used today is DOS or MS DOS.
Application programs are written by programmers to perform a specific function for the user. These might include word processing programs like WORD or WordPerfect, or specialty programs like Flight Simulator or MS Golf.
The tools used by programmers to create these application programs include programming languages. Examples of well-known programming languages include: C, C++, Java, Turing, Basic, Visual Basic and Pascal.
Bits, Bytes, Megabytes and Gigabytes
Computers work in binary. Information inside of computers is coded using 0's and 1's. One zero or one is called a bit. Eight bits make a byte. All the alphabetic and numerical values can be translated to 8 digits (1 byte) using a standard coding system called the ASCII code. For instance the letter J is coded as 0100 1010 and a blank is coded as 0010 0000. One million (106) bytes make a megabyte (MB) and 1,000,000,000 (109)bytes make a gigabyte (GIG or GB).
Magentic disks are used to store information on the computer. Information is organised on the disk using files and directories or folders. The hard or fixed disk that is located inside the system unit of your personal computer (PC) is called the local hard drive. (Usually this is named C: drive) The computer on which this document was created has 6 GB (gigabytes) of space on the hard drive. As well the PC has smaller "floppy" disks to store data. These typically can store 2 MB (megabytes) of information. Larger "zip" disks can be also used. These typically store 100 to 500 MB of information.
RAM (Random Access Memory)
Random access memory is used by the operating system to temporarily store the programs and information which are actively in use. The items stored here are readily accessible to the CPU. This memory is considered volatile because everything stored in it is erased when the computer is turned off. When computer advertising refers to memory, it is refering to RAM. ) The computer on which this document was created has 64 MB of RAM.
Computers that are linked together in order to send information to one another are networked. PC's that are not linked are called stand-alone. One main computer (file server) is linked to all the others by cable or by radio signals. At SCS we use a star network, where are the computers are linked as in the diagram to the right. In this configuration, one PC may stop functioning, but none of the others are affected.
Other networks can be in a bus format or a ring format.
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updated June 9, 2001