1. Computer Structure

2. We will look at:  Four Box diagram  CPU  Memory  Registers and their role  Processing speed

3. Input Output Backing Store Processor Memory (RAM and ROM) CPU Four Box Diagram

4. Basic concepts - Hardware Central Processing Unit (CPU) performs actual processing of data. Central Processing Unit (CPU) performs actual processing of data. Data and programs are stored in memory, and moved to and from CPU as required. Data and programs are stored in memory, and moved to and from CPU as required. Data travels between system components along electronic pathways, (sets of wires), called buses. Data travels between system components along electronic pathways, (sets of wires), called buses.

5. Three major components of the CPU: Arithmetic and Logic Unit (ALU), Control unit Registers

6. Arithmetic Logic Unit: Functions The main functions of the ALU are: To perform arithmetic calculations (addition, subtraction, multiplication and division) To perform logic functions involving branching ( IF, THEN)

7. Control Unit: Functions The Control Unit Controls the timing of operations within the processor. Sends out signals that fetch instructions from the main memory. Interpret instructions. Carry out instructions that are fetched from the main memory.

8. Registers These are temporary storage areas within the processor that are used to hold data that has been fetched from the memory or produced a calculation.

9. Main Memory Main Memory is composed of Read only Memory (RAM) and Random Access Memory (ROM)

10. Read Only Memory (ROM) n Features of ROM n Data in ROM is permanently etched onto a microchip n ROM is read-only memory and cannot be changed n Data on ROM is not lost when the computer is switched off.

11. Random Access Memory (RAM) n Features of RAM n The data in RAM is read/write so it can be changed. n All data stored in RAM is lost when the computer is switched off. n RAM is sometimes referred to as primary storage.

12. Types of Computer Systems Desktop Computers Portable ( laptops, palmtops) Mainframe Computers Embedded Computer Systems

13. Compare Computer DesktopPortable Processing Power3.2 GHz2.4 GHz Backing StorageHard Drive, CD Rom drive, DVD- RW Hard drive, removable floppy drive, DVD-ROM, CD-RW Input DevicesMicrophone, Keyboard, webcam mouse Pointing stick, touch pad, keyboard Output DevicesPrinter, monitor, speakers, modem, network interface card. LCD screen, inbuilt speakers, modem, NIC, USB

14. Palmtops Palmtops are very small portable computers, they have limited memory and processor speed. You required a stylus to input data, some palmtops have a microphone so you can use voice input, they also have a (limited) keyboard

15. Laptops Laptops usual have devices that are removable this makes the laptop cheaper to buy as you only purchase the devices that you require. It also makes the laptop lighter, for carrying.

16. Palmtop Applications A palmtop can use most applications but they will be cut down version of the usual package with limited functions

17. Mainframe Computer This system operates by sharing a processor between a large number of terminals. Mainframes support multi-access and multi-programming

18. Features of a Mainframe A mainframe will have several processors that work together making the machine extremely powerful. There is usually vast amounts of memory It typically has 100Gb of hard disk and tape drives are used for back ups. A keyboard is the input device Printers and monitors are the output devices.

19. Embedded Computer Systems This is a system which performs a specific task and is general part of a larger system that may not be a computer, it works in real-time and this is affected by time constraints.

20. Applications of Embedded Systems Products: washing machines, fridges, Electronics: cameras, camcorders, phones Industrial: printers, faxes, elevators, robots Multimedia: video conferencing, interactive games