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)
- mouse/trackball
- touchpad
- pointing stick/joystick/ touch screen
- graphics tablet
- stylus
-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
- 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.
-scanners capture and digitalize printed pictures
Flatbed: create comp files Slide: can only scan slides Drum: Sheet-fed
Snapshots images store as bits
microphones input devices
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:
- impact printers: they form images by physically striking paper, ribbon, and print hammer together like a typewriter
- line printers: only print characters
- Dot-matrix printers: prints texts and graphics
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:
- Tower System: tall, narrow that generally have more exansion slots and bays than other designs.
- Flat Desktop Systems: designed to sit under the monitor like a platform
- All-in-one System: combine monitoring and system unit into a single housing
- Laptop Computers: include all the essential components - keyboarding, room service
