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.
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
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
Computer Systems Internal Memory Holds the data & instruction that the CPU is currently working with. Secondary (Backing) Storage. Used to store data & programs
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 )
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 ).
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
Types of Computer Mainframe computers Cost Millions ££££££££££’s Can process massive amounts of data extremely quickly. Used by banks, utility’s tax office etc…
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.
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.
Types of Computer Palmtops/PDAs (Personal Digital Assistants), Perform basic functions of Word Processing, Spreadsheets, Calendars, Address Book and . The information can be transferred to a full size computer.