1. Computer Types
Unit One

2. A computer that processes request for HTML and other documents that are components of Web pages.
Purpose is to “serve.”
A computer that has the purpose of supplying its users with data; usually through the use of a LAN (Local Area Network).
Server

3. Workstation

4. Desktop computer which is usually more powerful than a Microcomputer.
Powerful desktop computer designed for specialized tasks.
A microcomputer that fits on a desk and runs on power from an electrical wall outlet.
The CPU can be housed in either a vertical or horizontal case.
Has separate components (keyboard, mouse, etc.) that are each plugged into the computer.
Workstation

5. Desktop Microcomputer
Small computer based on a microprocessor.
A personal computer designed to meet the needs of an individual; provides a variety of applications.
Provides access to a wide variety of computing applications, such as word processing, photo editing, , and internet.
Desktop Microcomputer

6. Portable, compact computer that runs on a wall outlet or battery unit with all components in one unit.
All components (keyboard, mouse, etc.) are in one compact unit.
Usually more expensive than a comparable desktop.
Sometimes called a notebook.
Laptop or Notebook

7. Tablet PC - Handheld

8. Handheld PC(PDA)

9. Smart phone - Handheld

10. Handheld Also called a PDA (Personal Digital Assistant).
A computer that fits into a pocket, runs on batteries, and is used while holding in your hand.
Typically used as an appointment book, address book, calculator, and notepad.
Can be synchronized with a personal microcomputer as a backup.
Handheld

11. AUXILIARY STORAGE DEVICES
Network Drive (H: drive)
Hard Disk Drive (C:drive)
Floppy Disk Drive with 3 ½” Floppy Disk (A:drive)
Smart card
CD Read/Write Drive
Zip Drive
Digital Audio Tape
AUXILIARY
STORAGE
AUXILIARY STORAGE DEVICES

12. Printers
Two main types:
Laser
Ink jet
Printers

13. Laser Printer Example Laserjet 5000 Series from Hewlett Packard Co.(
Laser Printer Example

14. Four steps
A laser is fired in correspondence to the dots to be printed. A spinning mirror causes the dots to be fanned out across the drum. The drum rotates to the next line, usually 1000th or 1600th of an inch. The drum is photosensitive. As a result of the laser light, the drum becomes electrically charged wherever a dot is to be printed.
Laser
Spinning mirror
Photosensitive drum
How it works

15. Operation of a Laser Printer
Four steps
A laser is fired in correspondence to the dots to be printed. A spinning mirror causes the dots to be fanned out across the drum. The drum rotates to the next line, usually 1000th or 1600th of an inch. The drum is photosensitive. As a result of the laser light, the drum becomes electrically charged wherever a dot is to be printed.
Laser
Spinning mirror
Photosensitive drum
Operation of a Laser Printer

16. Operation of a Laser Printer
Four steps
A laser is fired in correspondence to the dots to be printed. A spinning mirror causes the dots to be fanned out across the drum. The drum rotates to the next line, usually 1000th or 1600th of an inch. The drum is photosensitive. As a result of the laser light, the drum becomes electrically charged wherever a dot is to be printed.
Laser
Spinning mirror
Photosensitive drum
Operation of a Laser Printer

17. Operation of a Laser Printer
2. As the drum continues to rotate, the charged part of the drum passes through a tank of black powder called toner. Toner sticks to the drum wherever the charge is present. Thus, the pattern of toner on the drum matches the image.
Operation of a Laser Printer
Toner

18. Operation of a Laser Printer
3. A sheet of paper is fed toward the drum. A charge wire coats the paper with electrical charges. When the paper contacts the drum, it picks up the toner from the drum
Paper
Charge wire
Operation of a Laser Printer

19. Operation of a Laser Printer
4. As the paper rolls from the drum, it passes over a heat and pressure area known as the fusing system. The fusing system melts the toner to the paper. The printed page then exits the printer. As the same time, the surface of the drum passes over another wire, called a corona wire. This wire resets the charge on the drum, to ready it for the next page.
Corona wire
Fusing system
Operation of a Laser Printer

20. Specifications ppm dpi Pages per minute Typically 4-10 ppm
Dots per inch
Typically dpi
Specifications

21. Background Inkjet technology was developed in the 1960s
First commercialized by IBM in 1976 with the 6640 printer
Cannon and Hewlett Packard developed similar technology
Also called bubble jet
Background

22. Inkjet Printer Example

23. Three main types
Flatbed
Sheet-fed
Handheld
Scanners

24. How it works A scanner works by digitizing an image.
A scanning mechanism consists of a light source and a row of light sensors.
As light is reflected from individual points on the page, it is received by the light sensors and translated to digital signals that correspond to the brightness of each point.
Colour filters can be used to produce colour images, either by providing multiple sensors or by scanning the image three times with a separate colour filter for each pass.
The resolution of scanners is similar to that of printers, approximately dpi (dots per inch).
How it works

25. Flatbed Scanner Example

26. Sheet-fed Scanner Example
OfficeJet Series 700 from Hewlett Packard Co (
Sheet-fed Scanner Example

27. Handheld Scanner Example
QuickScan GP Bar Code Scanner from PSC, Inc. (
Handheld Scanner Example