Code Readers

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Barcode Readers

Barcode readers convert sequences of black and white strips to a digital format to send to a microprocessor.

How does it work?

Barcodes are machine-readable binary numbers represented by black and white lines.
A barcode reader directs a red laser onto a barcode.
- The white strips of the barcode reflect light back into the reader, which is registered as a '1' in binary.
- The black strips do not reflect the light back into the reader, so this is registered as a '0' in binary.

Applications

Barcode readers are used extensively in shops and supermarkets to:
- Identify items.
- Quickly find the price of products at the checkout.
- Monitor stock levels of items using automatic stock control.
Barcode readers are used to track the transport of items like luggage.
Libraries use barcodes to track books that are borrowed using a digital system.

Advantages of barcodes

Scanning barcodes is much faster than entering long numbers by hand.
Staff in shops don't need to remember or type in the prices of products.
- Accurate receipts can be given to customers quickly in shops.
Businesses can automatically generate reliable sales and stock reports.
Prices can be changed immediately without changing any barcodes.

Disadvantages of barcodes

Barcodes can only store long numbers.
Any extra information must be stored in a database linked to the barcode number.
Barcodes can be difficult to scan if damaged.
Highly reflective objects are hard to scan and identify using barcode readers.

QR Code Readers

Quick response (QR) codes are two-dimensional barcodes capable of holding approximately 7000 digits. These digits are accessed by scanning the pattern with a QR code reader.

How does it work?

QR codes are matrix (2D) barcodes.
QR codes contain marker squares that are used by the camera to position and align the scanned image.
QR code readers work similarly to barcodes by reading the light that is reflected off the white parts of the QR code.
Smartphone cameras can be used as a scanning device.

QR code structure

Applications of QR codes

QR codes can be used to hold contact information, calendar entries and product details.
QR codes are most often used to direct viewers to a specific web page.
- QR codes are used in advertising on public transport.
QR codes are also used in digital ticketing systems.
Ticket holders can show the QR code on their phone instead of having to print out tickets or wait for them to arrive in the post.

Advantages of QR codes

QR codes are very accessible as most smartphones can scan them.
QR codes are a simple way to send users to website URLs that are often long and difficult to type by hand.
QR codes can hold a larger amount of information than barcodes due to the second dimension.
QR codes can link to further information that is too dense for adverts.

Disadvantages

Changing the underlying data changes the pattern of a QR code.
- You must update the pattern every time you change the data.
- This means QR codes are not suitable for data that changes regularly like prices.
Users need a device with a camera and software that can read QR codes.

1Computer Systems

1.1Data Representation

1.1.1Binary Numbers

1.1.2Negative Binary Numbers

1.1.3Hexadecimal

1.1.4Using Hexadecimal

1.1.5Converting Binary & Hexadecimal

1.1.6Converting Denary & Hexadecimal

1.1.7Capacity

1.1.8Calculating Capacity Requirements

1.1.9Binary in Computer Systems

1.1.10Data Compression

1.1.11Run Length Encoding

1.1.12File Formats

1.2Data Transmission

1.2.1Packet Switching

1.2.2Data Transmission

1.2.3Universal Serial Bus (USB)

1.2.4Parity Check

1.2.5Checksum & Echo Checks

1.2.6Encryption

1.3Hardware

1.4Software

1.4.1Operating Systems

1.4.2Interrupts

1.4.3High-Level Languages

1.4.4Low-Level Languages

1.5The Internet & its Uses

1.5.1The Internet

1.5.2Uniform Resource Locators (URLs)

1.5.3DNS

1.5.4HTML

1.5.5Cookies

1.5.6Web Hosting

1.5.7Digital Currency

1.6Cyber Security

1.6.1Forms of Attack

1.6.2Penetration Testing

1.6.3Types of Malware

1.6.4How Malware Spreads

1.6.5Protecting Against Malware

1.6.6Information Security

1.6.7Structured Query Language (SQL) Injection

1.6.8Firewalls

1.6.9Authentication: User Access Levels

1.6.10Authentication: Passwords

1.6.11Social Engineering

1.6.12Phishing

1.6.13Denial of Service Attacks

1.7Automated & Emerging Technologies

1.7.1Automated Systems

1.7.2Robotics

1.7.3Artificial Intelligence

2Algorithms, Programming & Logic

2.1Algorithm Design & Problem Solving

2.1.1Computational Thinking - Abstraction

2.1.2Computational Thinking - Decomposition

2.1.3Computational Thinking - Algorithmic Thinking

2.1.4Pseudocode

2.1.5Flow Diagrams

2.1.6Interpreting, Correcting & Completing Algorithm

2.1.7Correcting Algorithms

2.1.8Completing Algorithms

2.1.9Testing

2.1.10Types of Testing

2.1.11Test Plans

2.1.12Validation & Sanitation

2.1.13Authentication & Contingencies

2.2Programming

2.2.1Programming Fundamentals - Variables & Constants

2.2.2Programming Fundamentals - Comments

2.2.3Programming Fundamentals - Input & Output

2.2.4Data Types

2.2.5Casting

2.2.6Controlling Program Flow - Sequence

2.2.7Controlling Program Flow - Selection

2.2.8Controlling Program Flow - Iteration

2.2.9Modularity - Subroutines

2.2.10Modularity - Scope

2.2.11Arrays

2.3Databases

2.3.1Structuring Data - Records

2.3.2Structuring Data - Databases

2.3.3SQL

2.4Boolean Logic

2.4.1Binary Systems

2.4.2Logic Circuits

2.4.3Truth Tables

2.4.4Evaluating Expressions

2.4.5Boolean Operators

2.4.6End of Topic Test - Logic

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