Computer Systems I’m ONLY a machine!

Hardware Hardware refers to all the parts of the Computer System that we can touch. An item of hardware is called a device. Microprocessor Main memory Input / Output Backing Storage

Central Processing Unit CPU Input Output RAM ROM Backing Storage

The Processor Carries out the actual process Follows a set of instructions called a program Like a brain but can’t think or act for itself INPUT PROCESS OUTPUT

Representing Graphics & Text Bit-Mapped Graphics Dots called pixels Each pixels is either On (1 – black) or Off (0 – white) Text – ASCII standard file format 0100110101010101010010100101010001000000101000010001000000100001001000101001000000101000101010101010010010100010101010100 = MUJTABA BE QUIET

Units of Storage Binary Unit Value Bit 1 or 0 Byte 8 bits Kilobyte (KB) 1024 bytes Megabyte (MB) 1024 Kilobytes Gigabyte (GB) 1024 Megabytes Terabyte (TB) 1024 Gigabytes

Main Memory CPU Input Output RAM ROM Backing Storage

Main Memory Where the computer stores programs & data Types: RAM ROM Random Access Memory ROM Read Only Memory

Main Memory ROM Chip Permanent storage Data is safe when computer is switched off Data can not be added to ROM Some OS are stored on ROM Chips RAM Chip Temporary storage Data is lost when computer switched off Data can be written to RAM Upgrading is easy with RAM Chips

Input CPU RAM Backing Storage Input Output ROM

Input Devices (Navigational) Mouse Trackball Track pad Touch Screen Joystick SmartBoard

Input Devices (Data Input) Keyboard Graphics Tablet Scanner Digital Still camera Digital Video Camera Webcam Microphone

Backing Storage CPU RAM Backing Storage Input Output ROM

Backing Storage Method used to physically store data. Constantly increasing in capacity to meet demands. Magnetic Storage Floppy disc, Hard Disc, Magnetic Tape Optical Storage CD, DVD Solid State USB Flash Drive

Drive or Media Drive Media

Magnetic Storage Hard Disk Drive Floppy Disk Magnetic Tape Usually main type of backing store Non-removable media Floppy Disk Plastic disk with rectangular cover Removable media Magnetic Tape Sequential Access Think VHS tape Easy to damage – put next to magnet it will be wiped

Optical Storage

Optical Storage CD-ROM DVD-ROM CD-Recordable (CD-R) / DVD-R Read by a laser beam that reflects of surface “pits” and “lands” DVD-ROM Similar to CD but with larger capacity because of multiple layers CD-Recordable (CD-R) / DVD-R Write Once, Read Many CD-Rewritable (CD-RW) / DVD-RW Still uses a laser but contents can be changed Advantages – high storage capacities Disadvantages – Harder than mag but still easy to damage

USB Flash Drive Universal Serial Bus: Solid State Memory Advantages Computer interface used by different devices. Solid State Memory No moving parts Advantages Portable Can have large memory (currently 8GB) Goes through the wash

Flash Memory Cards Solid State Memory Advantages No moving parts Used in cameras and mobile phones Advantages Portable Can have large memory (currently 8GB) Can be read by a card reader Goes through the wash

Output CPU RAM Backing Storage Input Output ROM

Comparison of Printers Output Devices Printer Laser Inkjet Comparison of Printers Resolution Dots Per Inch (DPI) Speed Pages Per Minute (PPM) Cost Capital Cost Running Costs

Output Devices Plotter Monitor (VDU) LCD TFT Multimedia Projector Liquid Crystal Display TFT Thin Film Transistor Multimedia Projector Speakers

Types of Computer Desktop Laptop/Notebook Palmtop Think about the different I/O

Types of Computer Mainframe Think about the different I/O