Ch3 Hardware Basics

OBJECTIVES

KEYBOARD

• the most familiar input devices
• used to enter letters, numbers, and special characters
• standard keyboards
•  Ergonomic keyboards: adress medical problems
• wireless and onehanded keyboards
• folding keyboards: used with small computers (palm-sized)

POINTING  DEVICES

• mouse/trackball
• touchpad
• pointing stick/joystick/ touch screen
• graphics tablet
• stylus

-mouse is designed to move the pointer around the screen.
-touchpad is sensitive to light pressure
-pointing stick: tiny handle that sits in the middle of the keyoard and response to finger touches
-trackball: a mouse with a ball on the side and user uses that ball to move the pointer on the screen

READING TOOLS

• codes that are specifically used to input on the computer

Examples of reading tools are:

• optical-mark readers: uses reflected light to determine the location of pencil marks on test answer sheets.
• magnetic-ink character readers: reads odd shaped #s
• Bar-code readers:codes created from patterns
• pen scanners: can capture text from a printed doc and transfer it to a PC
• tablet PC
• smart whiteboards
• radio frequency identification readers: uses radio waves to comm.

digitalizing the world
-scanners capture and digitalize printed pictures

• Flatbed: create comp files
• Slide: can only scan slides
• Drum:
• Sheet-fed

DIGITAL CAMERA

• Snapshots
• images store as bits

AUDIO DIGITALIZERS

• microphones
• input devices

SIGNALS

• stored
• specialized software
• A digital signal processing chip compresses the stream of bits beforeit is transmitted to the CPU.

 

Speech recognition software

-converts voice data into words that can be edited

SCREEN OUTPUT

-monitor or videodisplay terminal (VDT) displays:

• characters
• graphics
• photographs
• animation

-video adapter: connects the monitor to the computer

-video memory: a special portion of RAM to hold images

-more video memories = more picture detailed displayed

-monitor size: is measured as a diagonal line

-resolution: number of pixels (tiny dots that compose a picture) on the screen

-higher resolution = dots closer together

-image quality is affected by resolution and color depth (number of different colors on the screen)

MONITOR CLASSES

- CRT (cathode-ray tubes)

- LCD (liquid crystal displays)

-Examples of LCDs are:

• Overhead projection panels
• video projectors
• portable computers (laptops)

PAPER OUTPUT

- printers produce papers (output, hardcopy)

-there are 3 groups of printers:

1. impact printers: they form images by physically striking paper, ribbon, and print hammer together like a typewriter
2. line printers: only print characters
3. Dot-matrix printers: prints texts and graphics

-and so many other kinds of printers like the nonimpact, the laser, the inkjet, the mulfunction, and the photo.

FAX MACHINES AND FAX MODEMS
facsimile machine: a fast and convenient tool for transmitting info. stored on paper.
fax modem: translates doc. into signals that can be sent over phone decoded by fax machines.

OUTPUT YOU CAN HEAR
sound card: allows PC to accept microphone input

CONTROLLING OTHER MACHINES
force feedback joystick: recieves signals from a comp and gives feedback that matches the visual output of the game.

 Storage Devices:

Input meets Output

- storage devices (secondary storage): perform both input and output functions, have both tape and disk drivers

-the comps primary storage is its memory

MAGNETIC TAPE

• Tape drivers can write data onto and read data off of a magnetically coated ribbon of tape. - are common storage devices on mainfram comps and some PCs
• Magnetic tape can store massive amounts of info in a small space at a relatively low cost.
• Sequential-access is the tapes limitation - comp must go through the info in order in which it was recorded

MAGNETIC DISKS

• Magnetic disks store encoded info
• Disk drive writes and reads data from the disk's surface - can rapidly info from and prt of the magnetic disk without going in order of recording.

- Internal hard drives and smalled microdries are based on very similar technologies, despite the diff size.

-all PCs use hard disks as their main storage device

• Hard disks are connected to the comp housing

OPTICAL DISCS

• optical disk drivers use laser beans rather than magnets to read and write bits of data on a reflective aluminum layer of the disk.

SOLID-STTATE STORAGE DEVICES

• flash memory: a erasable memory chip that can serve as a reliable, ow-energy, quiet, compact alternative to disk storage.
• USB store and transport data
• solid-state storage storage with no moving prts

The Computer System:

The Sum of its Parts

-there are 4 basic design classes for comps:

1. Tower System: tall, narrow that generally have more exansion slots and bays than other designs.
2. Flat Desktop Systems: designed to sit under the monitor like a platform
3. All-in-one System: combine monitoring and system unit into a single housing
4. Laptop Computers: include all the essential components - keyboarding, room service