How the processor handles instructions - Lesson 1

Understanding Software

Digital devices use different types of software to perform tasks. These are divided into:

• Applications software – Programs designed for specific tasks (e.g., word processors, web browsers, mobile apps).

• Systems software – Software that manages hardware and applications. It includes:

  • Operating System (OS) – Acts as an interface between hardware and users, allowing applications to run.

  • Utility Software – Maintains system performance, including:

    • Device drivers – Enable hardware components to communicate with the OS.

    • Security software – Protects against threats (e.g., antivirus, firewalls, anti-malware).

    • Disk defragmenter – Reorganizes fragmented files on the hard drive for better performance.

Operating System (OS) Functions

The OS is the backbone of any digital device. It:

• Manages hardware, including the processor.

• Runs applications and provides a user interface.

• Handles file storage and retrieval.

• Ensures smooth communication between software and hardware.

Without an OS, users cannot interact with the device.

​Security Software

Security software ensures the safety of a digital device. Examples include:

• Firewalls – Blocks unauthorized network access.

• Antivirus – Detects and removes viruses.

• Anti-spyware & anti-malware – Prevents harmful software from spying or damaging files.

• Biometric security – Uses fingerprint, facial recognition, or voice pattern recognition for authentication.

Passwords and PINs are also commonly used for security.

Disk Defragmentation

When files are saved, they may be stored in different locations on a hard drive, causing fragmentation.

• Fragmentation slows down performance as the OS takes longer to locate and open files.

• A disk defragmenter organizes scattered data, making access faster and improving efficiency.

​Data Storage Basics

All digital data is stored in binary format (1s and 0s).

• A bit (binary digit) is the smallest unit of storage.

• A byte (8 bits) can represent a single letter or number.

Data Storage Basics cont..

Unit	Equivalent

Bit (b)=

1 or 0

Byte (B)=

8 bits

Kilobyte (KB)

1,000 bytes

Megabyte (MB)=

1,000 KB

Gigabyte (GB)=

1,000 MB

Terabyte (TB)=

1,000 GB

Petabyte (PB)=

1,000 TB

Converting Between Storage Units

To convert from a smaller unit to a larger unit (divide by 1,000 each step):

• 1,000 bytes = 1 KB

• 1,000 KB = 1 MB

• 1,000 MB = 1 GB

• 1,000 GB = 1 TB

💡 Example:
5,000 MB = 5 GB (5,000 ÷ 1,000).

Converting Between Storage Units

To convert from a larger unit to a smaller unit (multiply by 1,000 each step):

• 1 GB = 1,000 MB

• 1 MB = 1,000 KB

• 1 KB = 1,000 bytes

💡 Example:
3 GB = 3,000 MB (3 × 1,000).

Why Data Storage Knowledge Is Important

• Helps determine if there is enough space on a device for a file.

• Makes it easier to manage files efficiently.

• Helps understand file sizes and storage limits (e.g., a high-resolution photo is ~5 MB, a movie is ~4 GB).

• Optimizes performance and speed when working with large files.

Example:

A word-processed document contains 300 characters, including spaces. Using this information, it is possible to work out how many bytes, kilobytes or megabytes are needed to store the file
Remember: the ASCII code that represents the character set of most computers is 8 bits.

Solution

• If each character is stored using 8 bits, that means that 300 x 8 bytes are needed to store the word-processed document. So, 300 x 8 = 2400 bytes.

• You can work out how many kilobytes are needed to store the file by dividing 2400 by 1000: 2400 ÷ 1000 = 2.4 kilobytes or 2.4 KB.

Exercise

• Another word-processed document is 6500 megabytes in size. How many characters are there in the file?

• A utility program stored on a computer hard drive is 30 megabytes in size. What is this file size in bytes?