Computer Basics - Hardware

Overview of Computers

1) PC – the Personal Computer; 2) Mac – the Apple Macintosh.

 Two designs of computers:  

1) desktop 


2) laptop (notebook)

 Inside the Computer

1) Processor:

        The CPU (Central Processing Unit), a complete computation engine that is fabricated on a single chip, is the computer’s brain. It is sometimes referred to as the central processor, microprocessor, or just processor.     Most newer PCs have Pentium processors. Pentium processors run faster than the numbered processors found in older computers (286, 386, 486 processors). The speed of processors, called the clock speed, is measured in megahertz (MHz) or gigahertz (1 GHz = 1000 MHz). One MHz represents one million cycles per second. For example, a processor that runs at 200 MHz executes 200 million cycles per second. 

 

2) Memory:
     

        RAM (Random Access Memory) is a working area where the operating system (e.g. Windows), programs and data in current use are kept, ready to be accessed by the processor. It is the best known form of computer memory.  The more RAM you have, the quicker and more powerful your computer is.

        Memory is measure in the following units:

       -  1 byte = 8 bits (Each 1 or 0 is called a bit (i.e. binary digit). Each character (i.e. a letter, a number, a space, or a punctuation mark) has its own arrangements of 8 bits, e.g. 01000001 = “A”, 01000010 = “B”.

-  1 KB (kilobyte) = 1024 (210) bytes

-  1 MB (megabyte) = 1024 (210) KB

-  1 GB (gigabyte) = 1024 (210) MB

       

 

 Storage Devices

The most common forms of storage devices in a home computer are:

- Hard disk drive

- Floppy disk

- CD-ROM

- CD-R and CD-RW

- DVD-ROM

- USB flash drives

1) Hard disk and hard drive (HD)

        A hard disk is a magnetic disk on which you can store computer data on a more permanent basis. The term “hard” is used to distinguish it from a soft, or floppy, disk. Hard disks hold more data and are much faster than floppy disks and optical disks. A hard drive is a mechanism that reads and writes data on a hard disk. The capacity of hard drives in newer PCs ranges from 20GB to 60GB in size since all software, from operating systems to word processors, and media files have grown tremendously in size over the last few years.

 

 

2) Floppy disk and floppy drive

         A floppy disk (often called floppy or disk) is a soft magnetic disk and a floppy drive is a mechanism that reads and writes data on a floppy. Unlike most hard disks, floppy disks are portable, because you can remove them from a disk drive. Floppy disks are slower to access than hard disks and have less storage capacity, but they are much less expensive.      Most modern floppy disks have 1.44MB of data storage. 

 

3) Optical disk and optical drive

         Optical disks can store information at much higher densities than floppy disks. Thus, they are ideal for multimedia applications where images, animation and sound occupy a lot of disk space. Besides, they are not affected by magnetic fields. This means that they are secure and stable; for example, they can be transported through airport metal detectors without damaging the data. However, optical drives are slower than hard drives.

        There are various types of optical disks and drives:

        A) CD-ROM (short for “Compact Disk-Read-Only Memory”) and CD-ROM drive

A CD-ROM, an optical disk onto which data has been written via a laser, can store everything, from shareware programs to dictionaries and encyclopedias, from multimedia databases to 3-D games. CD-ROMs are considered the most economical devices of storing and sharing information. For example, a CD-ROM (700 MB) can replace 300,000 pages of text (about 50 floppies), which represents a lot of savings in distributing materials and data. Yet, you can only read information on a CD-ROM but cannot write anything on it.

A CD-ROM drive is used to play CD-ROMs and it can also play audio CDs. CD-ROM drives are available in a variety of different speeds, the speed being described thus: 12x, 16x, 24x, 32x, 48x, etc. This indicates the speed at which data can be pulled off the CD-ROM drive. Higher-speed  CD-ROM drives help to transfer data more quickly, which is crucial when playing sound or video.

 

        B) CD-R, CD-RW and CD-R/CD-RW drive (also called CD-burner or CD-Recorder)

CD-R (short for “Compact Disk Recordable”) drives record data on CD-R disks (but write once only), allowing you to create and duplicate CD-ROMs and audio CDs. They can also be used to back up hard disks or to distribute and archive information. CD-RW (short for “Compact Disk Rewritable”) drives can erase and reuse data on CD-RW disks. In fact, to create CD-ROMs and audio CDs, you'll need not only a CD burner, but also a CD-R/CD-RW software package.

 

        C) DVD-ROM (“DVD” is short for “digital video disk” or “digital versatile disk”)

A DVD-ROM (or just DVD) is a type of optical disk technology similar to the CD-ROM. It can hold up to 17 GB of data, about 25 times an ordinary CD-ROM. For this reason, a DVD-ROM can store a large amount of multimedia software and complete movies in different languages. It can also play music CDs and CD-ROMs. DVDs are read-only devices. To avoid this limitation, companies also produce DVD-R/DVD-RW disks and DVD-burners.

 

4) USB flash drive

 

        A USB flash drive is a small, portable flash memory card that plugs into a computer’s USB port and functions as a portable hard drive with up to 2GB of storage capacity. USB flash drives are easy-to-use because they are small enough to be carried in a pocket and can plug into any computer with a USB drive. In addition, they are very durable because they do not contain any internal moving parts. USB flash drives also are called pen drives, key drives, or simply USB drives.

 

 Monitor

 

        There are two types of monitors available for PCs: the traditional CRT (cathode ray tube) and the newer LCD (liquid crystal display). The CRT is used for both televisions and computers. It produces a good quality image at a number of different settings for a reasonable price. LCD monitors, also known as flat panel displays, are used in laptop (or notebook) computers and more frequently for desktops as well. They are lighter and smaller (only inches thick) than CRTs with reduced electromagnetic emissions and power consumption.

 

 

  Ports

 

        A port is an interface on a computer to which you can connect a device. Personal computers have various types of ports. Internally, there are several ports for connecting disk drives, monitors, and keyboards. Externally, personal computers have ports for connecting modems, printers, mice, and other peripheral devices.

 

        There are three common types of external ports that usually come with a computer:

1) Parallel ports (for most printers)

2) Serial ports (for most modems and some mice)

 

 

3) USB (Universal Serial Bus) ports (for about every peripheral made in a USB version)

*Note: A “bus” is a set of conductors that carry signals between different parts of a computer

 

 

        The USB (Universal Serial Bus) provides a single, standardized, easy-to-use way to connect up to 127 devices to a computer. The USB connectors let you attach everything from mice to printers to your computer more quickly and easily than the other two. The operating system supports USB as well, so the installation of the device drives is quick and easy, too.


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