Types and Components of Computer Systems

Types and Components of Computer Systems

1. Types

   • Mainframe
     • A mainframe computer is a large computer, often used by large businesses, in government offices, or by universities. Mainframe computers are typically: Powerful - they can process vast amounts of data, very quicklyLarge - they are often kept in special, air-conditioned roomsMulti-user - they allow several users (sometimes hundreds) to use the computer at the same time, connected via remote terminals (screens and keyboards)
   • Personal or Desktop
     • The creation of computers that were small enough to fit on a desk, and cheap enough that everyone could have their own, personal computer, instead of having to share access to a mainframe. These computers came to be known as desktop computers, orpersonal computers (PCs). A typical PC contained the same basic components as a mainframe computer (CPU, RAM, storage, etc.) but at a fraction of the size and cost.
   • PDA or Personal Desktop Assistance
     • A PDA is similar to a palmtop computer, except it is even morecompact, and typically has no keyboard, using a touchscreen for all data input. Since the screen is so small, many PDAs have a small stylus (plastic stick) that is used to press things on the screen. Most PDAs use some sort of handwriting-recognition system to allow the user to write on the screen, and have their writing converted into text. PDAs tend to be used a 'digital diaries' allowing users to take their e-mail, documents, appointments, etc. with them wherever they go.
   • Laptop
     • A 'laptop' computer is a light, compact and portable PC.  Laptops contain a rechargeable battery so that they can be used even when not plugged in to a mains power supply. They also have a built-in LCD monitor. To make them as portable as possible, most laptops try to avoid any sort of cable or wire. Instead of a mouse, a trackpad is used. Instead of a wired connection to a network or printer, 'wireless' radio connections are used.
   • Palmtop
     • A palmtop computer is similar to a laptop computer, but smaller. It'ssmall enough to fit in the palm of your hand (hence the name!) Palmtops are usually not very powerful since fast CPUs require a large battery and get hot - both problems in a small device. A typical palmtop have a very small keyboard - too small to type on normally. Instead the user types using both thumbs. Also there is no room for a trackpad, so a touchscreen or tiny joystick is used instead. Palmtops are extremely portable, but the small keyboard and screen make the devices tiring to use for long periods.

2. Components

   • Hardware
     • CPU
       • is the 'brain' of the computer. It is the device that carries out software instructions.
     • Main Memory
       • RAM
       • ROM
     • Input
     • Output
     • Backing Storage
       • STORAGE DEVICE
   • Software
     • Operating Systems/ System Software
       • Graphic User Interface
       • Command Line Interface
     • Application Software