1.1 - What Computer Systems Are & How They Work
Data and information
Data consists of raw facts or figures without any context or meaning, such as a list of numbers or letters. When data is given context, it becomes information, which is useful and meaningful. The relationship can be expressed as: information = data + meaning.
Example of data becoming information
- The number 3460 is just data on its own, as it lacks context.
- If you add meaning, such as knowing it represents the distance in miles between London and New York, then 3460 becomes information.
Computers excel at processing large amounts of data quickly to produce information. For instance, a computer might take raw test scores (data) and calculate an average score (information) by applying mathematical rules.
How computers process data
Computers are electronic devices that take in data, manipulate it according to instructions, and produce results. This happens through a cycle of three main stages: input, processing, and output.
The input stage
Data enters the computer and is converted into binary form so it can be processed.
The processing stage
The data is manipulated or changed. For example, the computer might change a set of test scores into the average score.
The output stage
After processing, the computer presents the results to the user. Outputs can appear as text on a screen or printed documents.
Feedback loops in processing
Sometimes, the output from one cycle becomes input for the next, creating a feedback loop.
Binary representation of data
Computers use electrical circuits that are either on or off to represent and store data. This leads to a binary system, where data is encoded using only two digits: 0 and 1.
Key features of binary
- Each 0 or 1 is called a bit (short for binary digit).
- A circuit switched on represents 1, while off represents 0.
- Bits are combined to form codes; for example, 110101 is a 6-bit sequence.
- Binary is ideal for computers because it matches the simple on/off nature of electronic switches.
Units of data storage
Data in computers is measured in units based on bits, with each larger unit building on the previous one.
Common units of data
| Unit | Size | Description |
|---|---|---|
| Bit (b) | 1 binary digit | A single 0 or 1, the smallest unit of data. |
| Nibble | 4 bits | Often used to represent a single hexadecimal digit. |
| Byte (B) | 8 bits | Basic unit for storing a single character, like 'A'. |
| Kilobyte (KB) | 1000 bytes | Used for small files, such as short text documents. |
| Megabyte (MB) | 1000 kilobytes | Common for images or songs. |
| Gigabyte (GB) | 1000 megabytes | Typical for videos or software installations. |
| Terabyte (TB) | 1000 gigabytes | Used for large data collections, like hard drives. |
These units are often defined using multiples of 1000 for simplicity, but sometimes 1024 is used instead because it is a power of 2 (210 = 1024), which aligns better with binary calculations in computing.
Types of computers
Computers vary in size, purpose, and design to suit different needs. They range from tiny devices in everyday objects to massive systems for advanced research.
General-purpose computers
These are versatile machines designed for multiple tasks. Examples include personal computers (PCs) and smartphones. They can run various software, such as web browsers, games, or productivity tools, and often connect to the internet for communication.
Dedicated computers
These are built for a single, specific task and perform it efficiently. For instance, a computer controlling traffic lights is a dedicated computer.
Embedded systems
Embedded systems are dedicated computers built into other devices to control their functions. They usually manage specific operations.
Examples of embedded systems:
- The system in a television that processes signals to display images and adjust volume.
- The controller in a microwave that manages cooking times and power levels.
Computer hardware components
A computer system combines hardware and software to function. Hardware refers to the physical, touchable parts of the system, which can be internal (inside the computer case) or external (like peripherals). Internal hardware is connected via the motherboard.
Key internal hardware components
- Motherboard - The main circuit board that connects all other hardware components, allowing them to communicate.
- CPU (Central Processing Unit) - The brain of the computer, responsible for carrying out instructions and processing data; it is often covered by a fan to prevent overheating.
- RAM (Random Access Memory) slots - These slots hold RAM.
- Hard Disk Drive (HDD) - Provides internal secondary storage for long-term data retention, such as files and programs.
- Optical drive - Reads and writes data to optical discs, like CDs or DVDs, for storage or media playback.
- Power supply - Supplies power to all hardware components.
- Cooling fans - Keep internal components from overheating.