Introduction to Computer Systems

Introduction to Computers

• Understanding human-computer interaction requires knowledge of both humans and computers.
• HCI focuses on computers, their input/output devices, and how technology influences interaction and interface design.
• Interaction mirrors human interaction transferring information back and forth.
• The concept involves the exchange of information between user and computer.

Typical Computer System

• A standard setup includes a computer box, keyboard, mouse, and color screen.
• Hardware affects interface characteristics, varying across desktops, laptops, and PDAs.

Computer System Elements

• Input devices: Used for text entry and pointing.
• Output devices: Screens and digital paper.
• Virtual reality: Enables special interactions with dedicated display devices.
• Physical Interaction: Encompasses sound, haptic feedback, and bio-sensing capabilities.
• Paper: functions as both output (print) and input (scan).
• Memory: Includes RAM and permanent storage media and affects capacity and access.
• Processing: Focuses on processing speed and network capabilities.

Ways to enter text

• Keyboards (QWERTY layout)
• Chord Keyboards
• Phone pad using T9 entry
• Recognizing Handwriting
• Speech recognition technology

Keyboards Explained

• Keyboards: ubiquitous for text input
• Keyboards facilitating rapid text entry for skilled users.
• A keypress triggers a closed connection, sending a code for a character
• Keyboards are typically wired however wireless types are available.

QWERTY Keyboard Layout

• Letter & digit layout is fixed.
• Non-alphanumeric buttons vary.
• British keyboards use the pound (£) symbol.
• American keyboards use the dollar ($) symbol.
• The French AZERTY layout places main letters differently.

Alternative Keyboard Layouts

• Alphabetic layouts arrange keys in alphabetic order.
• These layouts do not improve speed for trained typists or beginners.
• Dvorak Layout places common letters under dominant fingers and is biased towards the right hand.
• Common letter combinations alternate hands and offers 10-15% Improvement in speed and reduction in fatigue.
• Widespread use of QWERTY creates market pressure to keep using QWERTY.

Chord Keyboards Explained

• Chord keyboards use few buttons (4 or 5).
• Letters are entered simultaneously.
• Microwriter uses patterns which reflect letter shapes.
• Chord keyboards: small, easier to learn, and enable quick typing and suitable for one-handed usages.
• These keyboards tend not to mainstream due to unfamiliarity and niche use cases

Phone Pad and T9 Entry Explained

• Phone pads: use numeric keys with multiple presses.
• Each number corresponds to multiple letters; 2-abc, 6-mno, 3-def, 7-pqrs, 4-ghi, 8-tuv, 5-jkl, 9-wxyz.
• T9 can be surprisingly fast.
• "hello" = 4433555[pause]555666

Handwriting Recognition Details

• Converting handwriting to digital text is challenging.
• Accuracy issues occur due to differing handwriting styles.
• Capturing drawing style and shape is needed
• Online recognition (tracking real-time patterns) is more effective.
• Letter shapes change based on surrounding words.

Speech Recognition Insights

• Speech recognition is a promising but limited text entry method.
• Natural interaction using speech is more accessible.
• Recognizing natural language with vagueness, imprecision and speech pauses is difficult.
• System training is needed due to varied speech patterns, plus accents and background noise effect results.
• Usages in telephone/information systems, disabled assistance, hands-occupied tasks i.e. military.
• Speech Recognition can be used in existing and new systems.

Numeric Keypads - Explained

• Used for fast number entry
• Used in Calculators and PCs
• Are different for telephones.
• Common in ATMs

Pointing Devices Overview

• Pointing devices are vital to CAD.
• These let users point and select items directly/via pointer.
• Drawing with a mouse differs from drawing with a pencil.
• Besides a mouse are: trackballs, touch screens, tablets, eye gaze systems and more

Mouse Functionality

• Mousses are major to desktop computer systems.
• Cursors, body and wires make a mouse.
• Mice involve planar motion.
• Mice usually have 1-3 buttons which are use for selection.
• Desktop mice require area and do not tire out the user
• Foot mice exist as well, they are rare.

Touchpad Functions

• Touchpads of size ~2-3 inches (50-75 mm) square function as touch-sensitive tablets.
• Touchpads started with Apple Powerbooks but can replace mice.
• These are operated by stroking a finger.
• Stroke controls the pointer.
• Good 'acceleration' impacts settings, fast & slow.

Trackball and Thumbwheel Details

• Trackballs are inverted mice with rotating weighted ball
• They are compact, do not need more operating space and use extra buttons to select.
• Slower for drawing because long movements are hard.
• The usability depends on weight and texture.
• Trackballs are popular for games.
• Thumbwheels are cheap, move slowly and are for horizontal and vertical control.

Joystick and Keyboard Nipple

• Joystick is small and indirect.
• Palm boxes, sticks/shaped grips allow you to move the screen cursor
• Pressure governs velocity.
• Buttons enable selection, function as computer game controllers aircraft controls and for 3D Naviation

Touchscreen Functionality

• Touchscreens allow for direct selection of items using your finger or stylus.
• Light interruption, capacitance and ultrasonic reflection are technologies used in touchscreens.
• The device has fast, direct control.
• No pointing device is needed to select items from menus.
• Grease can impact small selections and mess drawing.

Stylus and Light Pen - Explained

• Stylus: A small pen-like pointer to draw directly on screen and may use touch or magnetic detection.
• Light pens are now rare, it uses light to work and is good for direct use although it can obscure the screen.

Digitizing Tablet Insights

• Digitizing tablets allow for freehand drawing or mouse navigation.
• These can be used for handwriting with character recognition.
• Large desks are needed and is sometimes awkward to use.

Eyegaze Systems Explained

• Eyegaze systems track where the user is looking using glasses, head/mounted boxes via sensors.
• Low lasers help to establish eye position from retina.
• Pricey, fast and accurate.
• Selection is good, drawing is not.
• Detecting intentional gazes can be hard with the tech.

Cursor Keys Explained

• Four keys govern the cursor (up, down, left, right).
• Cursor keys are cheap and slow.
• Cursor keys are mainly used in text editing.
• No clear layout, inverted layout.

Discrete Positioning Controls in Devices

• Phones, TVs control functions
• Mini joysticks are common.
• Left, right, and up, down positioning is common.
• Menu selection is also governed by such devices.

Display Device Types

• Bitmap screens (CRT & LCD)
• Large display and situational displays
• Digital Paper screens

Bitmap Display Characteristics

• Computer displays rely on bitmaps with colored dots/pixels in rectangular grids.
• Colour ranges vary between black and white and greyscale.

Bitmap Displays Measured

• Screen quality is measured by colours displayable at each icon
• Screen clarity is governed by resolution(resolution).
• Computer resolution from computer may be different for device's resolution, resulting in stretching or uneven borders..

Health Information when using Screens

• Sit far
• USe big fonts
• Take breaks.
• Don't use them in front of windows
• Work in good light
• if pregnant also thing about posture, ergonomics, and stress.

Liquid Crystal Display Features

• Smaller, lighter, and no radiation when using.
• LCDs are being used more on PDAs, portable docks
• Used also Digital watches, mobile phones and HilFi Controls.
• Key featues are there is polarised and transparent top plate and reflecting bottom plate.
• Light travelling through both crystal changes and gets polarised, also emitted light gives strain.

Insights Into Large Displays

• Gas plasma tech allows for big bitmap screen to be created.
• HDTV has 16:9 vs old 4:3 display ratios.
• Public information screens help to interact for large and small uses.

Digital Paper Information

• Digital paper is nascent display tech .
• Electronic flexible material functions like normal comptuer displays.
• The aim is to make sheets that can be given "soft" computer printouts.

Physical Controls and Sensors details

• Sensory input encompasses Sound, touch, feel, and even smell
• Physical controls: Manual buttons and dials.
• External and biological sensors impact inputs and outputs.

Understanding Sound output

• Auditory signals work beside displays.
• Beeps or Clanks help to communicate system feedback.
• Keyboards make sounds to tell that presses are working.

Using Touch, Feel, and Smells

• Touch perception relies on change detection
• Devices exist which simulate haptic feedback.
• Fragrances evoke memories, scent releases are emerging.

Physical Controls information

• Default buttons serve basic computer functions.
• Specialized control panels on devices cause differences in appearance design.
• Buttons found on microwaves improve cleanliness.

Environmental and Bio-sensing Capabilities

• Sensors in public bathrooms help water flow.
• Car sensors also turn on lights when door is open.
• Sensor types include: heat/motion.

Important info about Paper and Scanning

• Print technology overview
• Fonts, page description and WYSIWYG (What you see is what you get).
• Scanning is done with OCR.

Printing Factors

• DOTS allows for printing to work.
• Printer quality depends in dpi (dot resolution), more resolution equals more lines per dots and clearer imageries.
• Factors affect printers are dots size sequential nature, and off set.
• Factors of printer technology are;
• Resolution
• Width and spacing
• Speed
• Costs

Printer Types

• Inkjet Printers: great for houses, print images with ink known for multiple medium types
• Laser Printers print quickly in office, creates great graphics however is better when in black and white.
• Dot matrix Printers impact ink ribbon to paper, can print forms too.

Fonts Details

• A font is a text style.
• Examples inclue courier, helvetica, ptalaino, times roman with common size units being point
• Different symbols exist for fonts. Courier font Helvetica font Palatino font Times Roman font §´µº¿Â Ä¿~ (special symbol)

More Font Details

• The measure of width also matters, fixed width is common and variable width depends (Times new roman i&m)
• San-serif and serif determine if letter includes styles like square shapes.

Readablity of Text

• Lowercase can be easier to read due to shape.
• UPERCASE is better for names.
• Serif helps read long lines while sans helps while reading digital copy 

Page description languages

• The are languages to describe display by managing its layout and appearance.
• Helpful with consistency with creation of documents.
• Postscript and PDF = quality and exchange while HTML/xhtml handle what sites show and PCL helps the printer.

Insight Into Scanners

• Scanners make artwork to image.
• 2 types include flatbread; high-qual and handheld; portable easy to take pictures.

Insights Into How We Use Scanners

• Scanners aid in organization and preserve long life of documents and artwork in long term.
• Digital images and artworks benefit from graphic design
• Healthcare records, education notes also use scans too.

The Importance of Memory

• Short/longer term memory also has speed, capacity compression and format measurements.

What is short term memory

• RAM (random access) gives data to CPU and has key characteristics volatile is stored for processes.
• Measures in GB/TB

Long Term Memory - Explained

• A persistent form of data, stored on magnetic and optical discs that can be written to.
• Retains computer data while off.
• HDDs: is a magnetic based technology.
• Optical Disk: Uses laser technology, and used in CDs DVDs and Blu-rays and are for durability and backups.

Metrics for Speed and Memory

• Speed: Data can be read and written faster depending on the medium.
• Capacity: Amount of stored data.
• Data size: This book 2mb, bible 4.5mb, photo 10mb, video 10mb/s.

What compression is

• Compressing reduces file size making it efficient to transmit.
• There are 2 types of "lossy", and "lossless".
• Lossless won't impact quality, lossy often gets rid of some quality.
• Used reduce and save spaces and speed up transfers.

Details on Storage for Text

• Formatted and unformatted data is sent to platform
• Types include
  • txt - plain
  • rtf - basic
  • html - web formats for media
  • pdf - versatile format with saved formatting

Storage Formats - Media

• Image: JPEG/PNG/GIF
• Audio: MP3/WAV
• Video: MP4/AVI

What are the limits of how much data a computer can hold

• Limits exist with interacting and finite computing .

The Speed We Can Process Data And What That Affects.

• Processing needs speed and it has faults that affect speed.
• If it is slow, there's drawing problems which prompts for buffering solutions which delays it further.
• If it is too fast it ends users up to click multiple times, causing screen issues but also swaps and memory issues.

Overview of Network Computing

• Computers connected to gether help.
• This allows for greater flexibility in what can be done.
• Benefits include
• Sharing
• Communication
• Scalavility
• Flexibility

Key Features of the Internet

• The Internet links private, public, business, and government networks to help in resource.
• Common language protocols:
  • HTTP
  • HTTPS
  • TCP/IP
  • FTP
  • SMTP
  • DNS