1. Computer Systems Objectives: To gain an understanding of the types of computer systems. Be able to identify the main components. Understand the difference between Hardware & Software.

2. Computer Systems Hardware:  The name given to any part of a computer that you can actually touch. Input Devices Output Devices Central Processing Unit (CPU) Internal Memory Backing Storage Devices

3. Computer Systems Central Processing Unit (CPU)  Rather like the ‘brain’ of the computer  Carries out all the instructions of a computer program. Central Processing Unit (CPU) ALU Control Unit Main Memory Input and Output Devices

4. Computer Systems Internal Memory  Holds the data & instruction that the CPU is currently working with. Secondary (Backing) Storage.  Used to store data & programs

5. Different Types of Memory VOLATILE MEMORY (Primary Storage)  This is often known as internal memory or RAM (Random Access Memory).  When the computer is turned off, the memory is lost - this is why it is called VOLATILE (temporary).  Very fast and allows the computer to recall information quickly.  The typical speed is 70ns (one second = 1,000,000,000 nanoseconds = 10 9 )

6. Different Types of Memory NON-VOLATILE MEMORY (Secondary or Backing Storage )  When you turn the computer off, the data in secondary memory is kept.  Slower than primary memory.  The typical speed of a hard disk is 10 ms (one second = 1,000 milliseconds = 10 3 ).

7. Input & Output devices Input Devices  Gives you the means of putting instructions & data into the computer  E.g. Keyboard & Mouse Output Devices  Used to output information  E.g. Printer & Monitor

8. Types of Computer Mainframe computers  Cost Millions ££££££££££’s  Can process massive amounts of data extremely quickly.  Used by banks, utility’s tax office etc…

9. Types of Computer Desktop  Can't easily be moved around.  Cheaper than laptops.  Room to expand - e.g. extra memory, a 2nd hard disk, TV input card etc.

10. Types of Computer Laptop/Notebook  Portable and allow you to carry out your work anywhere  Battery life is limited and they need re- charging.  keyboard and screen can be quite small.  Difficult to upgrade.

11. Types of Computer Palmtops/PDAs (Personal Digital Assistants),  Perform basic functions of Word Processing, Spreadsheets, Calendars, Address Book and e-mail.  The information can be transferred to a full size computer.