Transcript Computer Systems - Shawlands Academy

Computer Systems
I’m ONLY a
machine!
Standard Grade Revision
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
Input
CPU
RAM
ROM
Backing Storage
Output
The Processor
• Carries out the actual process
• Follows a set of instructions called
a program
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
– 010011010101010101001010010101000100000010100001000
100000010000100100010100100000010100010101010101001
0010100010101010100
= 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
Input
CPU
RAM
ROM
Backing Storage
Output
Main Memory
• Where the computer stores programs &
data
• Types:
– RAM
• 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
Input
CPU
RAM
ROM
Backing Storage
Output
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
Input
CPU
RAM
ROM
Backing Storage
Output
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
– 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
– Removable media
Optical Storage
Optical Storage
• CD-ROM
– 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
USB Flash Drive
• Universal Serial Bus:
– Computer interface used by
different devices.
• Solid State Memory
– No moving parts
• Advantages
– Portable
– Can have large memory
(currently 8GB)
Flash Memory Cards
• Solid State Memory
– No moving parts
– Used in cameras and mobile
phones
• Advantages
– Portable
– Can have large memory
(currently 8GB)
– Can be read by a card reader
Output
Input
CPU
RAM
ROM
Backing Storage
Output
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
– Liquid Crystal Display
• TFT
– Thin Film Transistor
• Multimedia Projector
• Speakers
Types of Computer
• Desktop
• Laptop/Notebook
• Palmtop
Types of Computer
• Mainframe