3.2 - I/O devices 🖨⌨🖱 Flashcards
what does a barcode look like?
it’s got parallel dark/light lines to represent digits (different between the left and right sides) and three guard bars at both L/R ends + the middle
what happens when you scan a barcode?
the red light that reads the barcode gets reflected with the dark areas being read by sensors to generate patterns of digital data so a device can understand what’s inside the barcode
how can barcodes be beneficial to their users?
they make stock/price management much easier and cheaper to the point of auto-stock control being possible, can be linked to customer behavior-related data, and reduce checkout hassles like long waiting queues and charging errors
what does a QR code look like?
it looks like a matrix filled with light and dark pixels that can store URLs and stuff (getting more complex the more stored data there is in the QR code) as well as three large squares at the corners for alignment purposes
what happens when a QR code gets scanned by a mobile device?
it looks for any readable data-containing pixels in the code and decodes the data in it (eg. phone numbers/URLs/mobile payment details)
how are QR codes better than traditional barcodes?
they can hold more info in a single code with less error, just need a camera to be read, and are easier to transmit and encrypt
what problems can QR codes create?
there can be confusion between different QR code formats and they could potentially be used for malicious attagging
what kinda QR code contains a canvas area for logos and stuff?
the frame QR code
what happens when a digital cam takes a pic of something?
the light-sensitive cells in the camera lens that contain tons of CCDs create an analog image that gets converted into a digital file through an ADC that reads the analog image’s electrical signals for brightness and color data
what happens when you press a key on a physical keyboard?
a digital signal gets sent to the device’s CPU via the circuit board below it to be interpreted as the corresponding ASCII/Unicode value in an index file
what can frequent physical keyboard usage result in?
RSI (repetitive strain injury) - this can be prevented by using an ergonomic keyboard
how does sound get recorded using a microphone?
as soon as a device’s sound-recording function gets activated vibrations in the air outside start to be picked up by the mic’s diaphragm inside of which a copper coil moves around to induce an electrical current that then gets converted into digital sound by the ADC
how does an optical mouse work?
it uses a red LED at its base that gets reflected on the surface for a CMOS to generate pulses that get sent to a DSP thus allowing a device processor to find the mouse coordinates out and move the onscreen cursor to that location anywhere without ever trapping dirt
why are Bluetooth-powered optic mice better than wired ones?
they constantly send signals through pathways to the device processor to prevent signal losses and are also cheaper and more environmentally friendly
how do 2D scanners work?
when a piece of paper’s placed on a covered glass scanning panel it’s illuminated by a bright white light as a scan head moves across the paper to construct an image of it that then gets focused onto by a lens so the light it sees can be converted by a CCD into electrical currents containing the data the software on a device needs to produce a digital copy of that piece of paper
how can docs scanned by a 2D scanner be made digitally editable?
through the use of OCR tech that converts such docs into a text-based file format like OTF and DOCX
what are some examples of 2D scanners being used IRL?
in reading passports at immigration checkpoints and facilitating examiners’ marking processes
