Hardware The physical components of a computer system. Everything you can see and touch.

1. Hardware The physical components of a computer system. Everything you can see and touch. Block Diagram Input Devices Main Memory Backing Storage PROCESSOR Output Devices

2. Processor A processor is a chip that responds to and processes the basic instructions that drive a computer. The processor in a personal computer is often called a microprocessor. Pentium 4 Processor The processor is like the ‘brain’ of the computer system. (BUT not a real brain as a computer cant think or act for itself)

3. Computers can carry out instructions very quickly because the processor can process billions of instructions every second. Instructions Execution Action The process of carrying out the instructions in a computer program. A set of instructions that control how a computer works is called a program. The instruction is carried out.

4. Main Memory The processor can’t store a whole program at the one time. A computer must have memory to store programs and data its not using at any particular time. There are two types of memory chips used for a different purpose in a computer system. RAM and ROM

5. Random Access Memory (RAM) Is the place in a computer where the operating system, application programs, and data in current use are kept so that they can be quickly reached by the computer's processor. RAM is much faster to read from and write to than the other kinds of storage in a computer. The data in RAM stays there only as long as your computer is running. When you turn the computer off, RAM loses its data.

6. Read Only Memory (ROM) ROM can be used to store programs and data permanently. Data cannot be easily written to ROM, depending on the technology used in the ROM, writing may require special hardware, or may be impossible. A computer's BIOS may be stored in ROM

7. RAM V’s ROM RAM RAM holds programs and data temporary. Program and data are lost when the computer is switched off. RAM holds programs that are currently running on your computer. ROM ROM holds programs and data permanently. The contents of ROM are not lost when the computer is switched off. ROM hold programs that has been programmed onto the chip at the factory and cannot be changed http://video.howstuffworks.com/hsw/player.htm?v=Computer_Tour

8. Change in Technology • The price of memory chips is continuing to go down. • The memory size of computers (ROM and RAM) has gone up. • Chips work faster and can handle more data in a single operation. • Complete computers can be produced on a single chip. • Computers are now tiny, for example palmtop computers.

9. Types of Computers • Palmtop Computer • Laptop Computer • Tablet Computer • Desktop Computer • Server Computer • Mainframe Computer • Supercomputer

10. Palmtop Computer - Personal Digital Assistants (PDA) Palmtops are tightly integrated computers that often use flash memory instead of a hard drive for storage. These computers usually do not have keyboards but rely on touchscreen technology for user input with a stylus. Palmtops are typically smaller than a paperback novel, very lightweight with a reasonable battery life. Most types use a LCD screen as the input device.

11. Laptop Computer This is a compact type of computer that can run on batteries that is entirely portable. Normally has a hard disk, floppy disk and a CD-ROM drive. Uses an LCD/TFT screen as an output device. LCD use less power. Laptop computers typically use a track pad or a raised button to control the pointer on the screen.

12. Tablet Computer A type of notebook computer that has an LCD screen on which the user can write using a special-purpose pen, or stylus. The handwriting is digitized and can be converted to standard text through handwriting recognition, or it can remain as handwritten text. A keyboard can be attached for data entry.

13. Desktop Computer • Most desktops come with the following: • Monitor (LCD, TFT at an extra cost) • Full size keyboard (function keys, numeric keypad) • Mouse with a scroll wheel (wireless at an extra cost) • Hard Disk • Floppy Disk Drive (several manufactures do not include these) • CD-ROM Drive (may have a CD rewriter) • DVD-ROM Drive (may have a DVD rewriter) • Modem

14. Desktop Computer – cont.. • Loudspeakers • Microphone • Peripheral devices may come with your computer such as: • Printer • Scanner • Web Camera

15. Server Computer • A computer that delivers information and software to other computers (clients) linked by a network. • A network interface card is required in order to connect to a network. • Different types of servers: • File Server (storage of users programs and data) • Printer Server (queuing facility) • CD-ROM server (access data from one or more CD-ROMS held within it)

16. Mainframe Computer Very large computer system which can process very large amount of data at a high speed. It may be connected to hundreds of user terminals. Vast amount of RAM and many extra peripherals such as tape and disk drives. The ‘dumb’ terminal has no processor and no local storage devices. All that is required is a screen and a keyboard. Multi-tasking system More than one program running on a computer system at the same time Multi-access system More than one person using a mainframe computer system at the same time

17. Super Computer • Used for intensive mathematical calculations such as: • Weather and climate forecasting • Car Design • Aerospace Engineering • Digital Animation in motion pictures.