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• Everything stored by a computer is stored using Binary, indicated by 0 and 1
• Example: 37 in denary is 00100101 in binary, derived from 0+0+32+0+0+4+0+1

Floating Point Representation

• The mantissa and exponent are stored as separate numbers
• The number is recreated for calculations when needed

Extended ASCII Code

• Each character is represented by an 8-bit ASCII code
• 'V' is represented as 86, or 01010110 in binary

Vector Graphics

• Vector graphics store a picture by storing the attributes of each object to draw the shape
• Rectangle attributes: height, width, x coordinate, y coordinate, fill color, line color
• Ellipse attributes: cx, cy, rx, ry, fill color, line color
• Line attributes: x1, y1, x2, y2, line color
• Polygon attributes: x1, y1, x2, y2, x3, y3, fill color, line color (any shape with 3+ sides)

Bit-mapped Graphics

• Computers store each pixel in binary
• The number of bits per pixel depends on the number of colors in the image: more colors require more bits

Computer Architecture Components

• Control Unit: controls the sequencing of fetching, decoding, and executing instructions
• Arithmetic Logic Unit: performs all calculations and logical operations
• Registers: temporary memory locations within the processor

Memory Locations and Buses

• Each location within RAM has a unique address for reading/writing data correctly
• Address Bus: identifies the memory location for reading/writing
• Data Bus: transfers data between the processor and memory

Interpreters and Compilers

• Interpreter: translates one line of code at a time into machine code and executes immediately and is useful for testing, highlighting errors instantly
• Compiler: translates the entire program and saves the machine code version for repeated use and useful for program release

Environmental Impact from Computer Systems

• Approximately two billion computer systems are in use worldwide, each using energy
• Users should consider ways to reduce unnecessary energy consumption
• Reducing brightness and activating efficiency mode helps reduce energy consumption

Power Settings

• Power down settings: power-down after inactivity, control setting for single components
• Standby: reduces power consumption compared to being fully on

Firewalls

• Firewalls protect against suspicious access to a computer
• External access is either granted or denied by the firewall

Encryption

• Encryption encodes information to be unreadable if intercepted
• Only the sender and receiver can understand the encrypted information

Website Analysis

• End-user: the intended audience for the website (e.g., children, employees)
• Functional requirements: features the website must have (e.g., search a database)

Website Structure

• Linear: users move sequentially from page to page
• Hierarchical: page access depends on position within the hierarchy

Wireframing

• Wireframing is for designing visual web page layouts, showing:
• Navigational links: internal (within site), external (to another site)
• Absolute addresses: full URL
• Relative addresses: URL based on the current location

Website Consistency

• Maintain consistent design rules across all pages
• Relative vertical positioning: placement of text, graphics, audio, and video
• File formats: choice of media formats (text, graphics, video, audio)

Copyright, Designs, and Patents Act

• Protects text, graphics, video, and audio within a website
• Prevents unauthorized copying, use, or distribution without the owner's permission

Standard File Formats

• Audio:
• wav: uncompressed, high quality, large file size
• mp3: lossy compression, good quality, smaller file size
• Graphics:
• jpeg: lossy compression, no transparency/animation
• gif: lossless compression, animation/transparency, 8-bit
• png: lossless compression, animation/transparency, 48-bit
• Graphic Resolution: more pixels per inch means better quality, larger file sizes
• Color Bit Depth: more bits per color means more colors, larger file sizes
• Sampling Rate: more samples per second means more realistic audio, but larger file sizes

Need for Compression

• Reduces file size for storage and faster transfer online

Prototyping

• A draft interface is produced early in development
• It resembles the intended look and feel of the final product

Cascading Style Sheets (CSS)

• CSS defines web page colors, fonts, and layout:
  • Internal Stylesheet: CSS code within the section of an HTML file
  • External Stylesheet: CSS in a separate file, linked to the HTML document
• Selectors: target HTML elements for styling using syntax such as H1 {color: blue; font-size: 12px;}
• ID: A unique identifier for an element, styled via CSS with #
• Class: applied to multiple HTML tags and styled via CSS with .classname

JavaScript Coding for Mouse Events

• Script tags enclose javascript code
• The color changes when the mouse hovers over or away with the ID demo

HTML Code

• <html> </html>: tells the browser the rest of the document contains HTML
• <head> </head>: contains information about the page itself – including CSS
• <title> </title>: title of the webpage, appears on browser tabs.
• <body> </body>: page content is placed between these tags.
• <h1> </h1>: creates a heading, there are six different sizes (h1 to h6)
• <p> </p>: defines a paragraph
• <div> </div>: used so CSS can be applied to a group of elements
• <a href = “link url”> link text </a>: creates a hyperlink – can take user to different page/ website
• <img src = “image url”>: inserts an image.
• <audio> <source src = “audio url”> </audio>: inserts an audio file
• <video> <source src = “video url”> </video>: inserts a video file
• List elements
  • <ol> </ol>: creates an ordered list - numbered
  • <ul> </ul>: created an un-ordered list - bulleted
  • <li> </li>: adds a list item

Hyperlinks

• internal and external
• relative and absolute addressing

Testing

• Code Examples make use of the above HTML
• Matches user-interface design
• Links and navigation function as intended
• Media (text, graphics, video) displays adequately
• The goal is consistency among pages

Evaluation

• Yes, when the website is fit for purpose
• No, the developer should revisit previous phases in the development process

Database Analysis

• End-user: what the end user wants to able to do with the database
• Functional requirements: the tasks the database should perform/ data it should hold

Data Protection Act 1998

• Ensures personal data is securely held and not shared
• Businesses must have prior consent, ensure accuracy, use data for limited purposes, and keep data secure

Entity-Relationship Diagrams

• Entity: a table
• Attribute: a field
• The diagram shows how the two relate

Data Dictionary

• A data dictionary includes the name and description of the attributes in each entity within a database

Attribute Type Examples

• Text: a combination of text and number e.g. name, address, telephone number
• Number: whole numbers and decimal numbers
• Boolean: true or false

Validation

• Validation makes it more difficult to make mistakes

Examples of Validation

• Range: ensures data is within a specified lower and upper limit
• Restricted Choice: limits the entry to a list of options
• Length Check: restricts the number of characters allowed
• Presence Check: ensures that the field is not left blank

Relational Databases

• Foreign key value has a matching value in corresponding primary key.

SQL operations

• SQL standard for Structured Query Language, it is used to interrogate data
• SELECT FROM: selects data : SELECT name, gender FROM student;
• WHERE: returns records that meet condition: SELECT name, gender FROM student WHERE regClass = "1S1";
• ORDER BY: ascending or descending: ORDER BY age ASC
• INSERT INTO: adds a record to a table
• UPDATE: modifies a current record
• DELETE: removes records
• EQUI-JOIN: displays result from two different tables, requires Primary Key & Foreign Key
• AND: must be true
• OR: ether must be true
• "<" less than
• ">" greater than

SQL Testing

• Expected results and actual results

Evaluation

• Requirements met
• Fit for purpose and accurate output
• If not, revisit

Software Development process

• Analysis
• Design
• Implementation
• Evaluation

Functional Requirements

• Inputs: data entered
• Processes: what happens to the data
• Output: the result
• Software follows the same diagram
• Flows charts - shows what is going on in a program and how data flows around it

Pseudocode format

• get age from user*
• if age < 15?*
• Send discount to user*
• else*
• Send no discount to user*
• end if*