COMP2 - Hardware Flashcards
Increasing Storage Capacity of an HDD
Use more platters.
Go perpendicular - magnets moved at right angles to platter.
Hard Disk Drive (HDD)
Has a platter (spinning disk) and head with polar fields. These change when it’s spun.
Stores data using the magnets which change polarity.
Platter is separated into sectors and tracks in concentric circles.
Laser Printer
Generates bit map of image.
Laser is modulated (turned on and off).
Laser removes charge on drum.
Toner is given charge and heated to fuse when on paper.
Ink Jet Printer
Heater behind ink reservoir is warmed to vaporise ink droplets.
Expands and forces ink blob on paper.
Electricity applied to crystal (deforms).
Prints line by line.
Ink dries before paper emerges.
Flat-Bed Scanner
Document placed onto glass pane.
Under pane are rows of red, green, blue LEDs.
Light sensor moved steadily under glass to scan document.
Reflected light converted to electrical signal.
More reflection from light regions than dark.
Reflected light represents colour used.
Bar Code Reader
Reads bar codes (series of white and black bars that stores information about a product).
Consists of light source, lens, detectors and decoder.
Scanner users light to illuminate bars - white bars reflect more like and dark reflects less.
Pattern of reflection converted to electrical form.
Scanner
Captures an electrical equivalent of a picture, text, handwriting or solid object.
Produces a digital representation for storing in a computer system.
Magnetic Stripe Reader
Information encoded magnetically - magnetic particles encased in plastic tape.
Can store up to 2KB - used on credit cards, library cards, railway tickets, phone cards etc.
Slow and steady swipe required to induce a current.
Smart Card Reader
Integrated circuit chip containing microprocessor, small amount of ROM, small amount of EEPROM, small amount of RAM, bus system.
Reader provides power when smart card inserted.
Applications stored in EEPROM and ROM - microprocessor executes applications.
Also used in credit/debit cards etc.
RFID Reader
Radio Frequency Identification uses radio frequencies to transmit data, a timing signal and energy between a reader and an RFID device.
Touch-Sensitive Screen
Type of visual display that a user can interact with.
User touches regions of screen. Just in front of screen is criss-cross of infrared light beams - breaking them is detected and co-ordinates mapped to control actions
Digital Still Camera
Electronic device to capture and store photos digitally on a memory card before uploading to a computer via a USB connection.
