Plymouth State University
The Four Functions of a Computer
INPUT
PROCESSINGOUTPUT
STORAGE INFORMATION
DATA
Plymouth State University
The System Unit
Power Supply
System Board
Hard DrivesorCD-ROM Drives
Floppy Drive
Expansion Card
Plymouth State University
Directions of Computer Development
• Miniaturization– Transistors– Integrated circuits
• Solid state
• Semiconductor
• Chip
Plymouth State University
Integrated Circuit
• IC, or "chip"
• Made from Silicon
• Includes Transistors, Resistors & Capacitors
Plymouth State University
Steps in Manufacture of a Microchip
1 Make large drawing. Reduce drawing hundreds of times to microscopic size.
2 Duplicate reduced photo many times on sheet.
Plymouth State University
Future Developments in Processing & Storage
• Moore’s Law– Gordon Moore predicted the number of transistors
on a silicon chip will double every 18 months– It has held up since the 1960s!
Plymouth State University
The System Unit: The Basics
• The CPU– Older CPUs processing speeds are in MegaHertz
• 1 MHz = 1 Million ticks per second
– Current CPUs processing speeds are in GigaHertz• 1 GHz = 1 Billion ticks per second
– The faster a CPU runs, the more power it consumes, and the more heat it generates
Plymouth State University
Secondary Storage, Primary Storage and the CPU
Main Memory(RAM)
CPUSecondary Storage
(Disk)
Load
Execute
Plymouth State University
How Memory Works: RAM, ROM, & Flash
• Types of memory chips:
1. RAM - Random Access Memory, used to temporarily hold software instructions and data
2. ROM
3. Flash
Plymouth State University
How Memory Works: RAM, ROM, & Flash
• Types of memory chips:
1. RAM
2. ROM - Read-Only Memory, which cannot be written on or erased by the computer user. Contains fixed start-up instructions
3. Flash
Plymouth State University
How Memory Works: RAM, ROM, CMOS, & Flash
• Types of memory chips:
1. RAM 2. ROM 3. Flash - can be erased and reprogrammed
more than once
Plymouth State University
Arithmetic/Logic Unit
Arithmetic 2 + 4 = 6 10 - 6 = 4
Logic 9 > 6 3 < 7 5 = 5
Plymouth State University
CPU Operation
Machine CycleTime it takes to process one machine instruction
Two parts:• Fetch Cycle - Get instruction, decode it, set up• Execution Cycle - Carry out the instruction
Plymouth State University
Two Types of Storage
• PRIMARY Storage - Main memory or RAM
• SECONDARY Storage - Auxiliary Storage (disks, Flash etc.)
Plymouth State University
Secondary Storage DevicesHard Disks
• Nonremovable disks– Known as a fixed disk– Capacity up to 1 terabyte +– Consists of 4 - 3.5 inch metallic platters
Plymouth State University
Secondary Storage DevicesOptical Disks
• CD – compact disk– about 700 megabytes – CD-ROM– CD-R– CD-RW
Plymouth State University
Secondary Storage DevicesOptical Disks
• DVD – digital video disk– 4.7 – 17 gigabytes– DVD-ROM – read-only– DVD-R – rewritable one time– Reusable types
• DVD-RW• DVD-RAM
Plymouth State University
Input and Output
INPUT - We provide the DATA to be processed
OUTPUT - We use the INFORMATION produced
Plymouth State University
Input & Output Hardware
Input hardwareTranslates words, numbers, sounds, and
pictures into numbers
Output hardwareTranslates numbers back into words, numbers,
sounds, and pictures
Plymouth State University
Some Input Devices
• Keyboards• Pointing devices
• Mouse• Trackball
• Touch screen• Pen input• Source data-entry devices
• Scanner• Text (OCR)• Voice• Video• MICR• FAX
Plymouth State University
Input Hardware
• Keyboards: convert letters, numbers, and characters into electrical signals– English keyboards differ from foreign language
keyboards
German Keyboard
Plymouth State University
Input HardwareWebcams and Video-input Cards
• Webcams– Video cameras attached to a computer to
record live moving images then post them to a website in real time
– Require special software, usually included with the camera
Plymouth State University
Input HardwareCamera Phones
• Digital cameras are now on cell phones– Convenience of being able to take photos, then
instantly email or message them to someone else
Plymouth State University
Input HardwareSource Data-Entry Devices
• Scanning devices – imaging systems
• Scanning devices – bar code readers– Magnetic-ink character recognition (MICR)– Optical-mark recognition (OMR)– Optical character recognition (OCR)
• Scanning devices – fax machines
Plymouth State University
Output Hardware
• Softcopy– Data that is shown on a display screen or
is in audio or voice form; exists electronically
– Output that is ephemeral in nature
• Hardcopy – Printed and film output– Output that is more permanent in nature
Plymouth State University
ResolutionResolution
..................................
Resolution = TOTAL PIXELS = # dots across by # dots down
Example: 1024 X 768
Plymouth State University
Output Hardware:Hardcopy Devices
• Impact printers– Dot-matrix
• Nonimpact printers– Laser– Ink-jet
Plymouth State University
Other Types of Output
• Projectors
• COM
• Machine Control
• Voice
• House Control Center
Plymouth State University
Health Matters
• Repetitive stress injuries– Carpal tunnel syndrome
• Eyestrain & headaches
• Back & neck pains
• Electromagnetic fields
• Noise
Plymouth State University
Ergonomics
• Fitting the job environment to the worker
• Purpose – make working conditions and equipment safer and more efficient
Plymouth State University
Ergonomic Considerations
• Chair
• Keyboard Height
• Wrist Rest
• Monitor Height
• Lighting
• Noise