2 – Under the Hood

🎯 Learning Objectives

Develop the Hardware & Processing learning strand:

  • Describe the hardware components used in computers and how they work together in order to execute programs
  • Highlight how all computing systems, regardless of form, are similar in structure (‘architecture’)
💬 Key Vocabulary

  • computer
  • data
  • hardware
  • processor
  • architecture
  • device
  • program
  • memory
  • storage
  • instructions
  • system
  • communication
  • input and output

📝 Starter Question

What is the main task of a general-purpose computing system?

  1. The main task is to execute programs.
  2. There is no main task. It can perform any task prescribed by a program.
  3. The main task depends on the system. Different systems may perform a different main task.
  4. The main task depends on the user. Different users may need the system to perform a different main task.

Answer

📖 A machine playing noughts and crosses

In the previous lesson, a human executed a program for noughts and crosses.

Question: What do you think it would take for a machine to be able to execute that program?

Answer

The physical components of a computing system are called hardware.

Hardware is any component of a computing system that you can touch.

The programs of a computing system are called software.

📝 Activity 1 – Check the Specs

The handout below contains specs for a range of modern computing devices.

Use the worksheet to say which components are present in each of these computing systems?

Definition

Specifications or ‘specs’: a table of hardware components and technical characteristics

📖 Insight

Diverse computing systems have strikingly similar components:

all computing systems are similar in structure (‘architecture’).

Let’s examine:

  • What the common components do
  • How they function together in order to execute programs

📖 Storage – What does it do?

The storage (secondary memory) is the set of components that stores programs and data.

Storage is persistent: it retains its contents when the power is off.

Common Storage Devices

Hard disk drives (HDD), solid-state drives (SSD), USB flash drives or USB sticks, SD cards.

📖 Memory – What does it do?

The main  memory  is the component that stores the programs and data currently in use.

Memory is volatile: its contents are lost when the power is off.

Terminology: The main memory is commonly referred to as RAM (random-access memory).

This is what the main memory looks like in desktops and laptops.

How it works with other components

When a program must be executed, it is loaded from storage in memory, along with the data required.

Any new or modified data must be saved from memory to storage.

📖 Processor – What does it do?

The processor is the component that executes program instructions.

An instruction may:

  • Perform arithmetic or logic operations on data
  • Perform input/output of data
  • Control program flow

Terminology: The processor is commonly referred to as the CPU (central processing unit).

This is what the processor looks like in desktops and laptops.

How it works with other components

Instructions are fetched one by one from memory into the processor, along with any required data.

The processor decodes and executes each instruction.

Any resulting data is moved into memory. 

📖 An analogy

Knitting patterns, yarn supplies, half-finished and finished projects are kept on the shelves.

This is the storage for programs and data.

When the knitter works on a project, the knitting pattern and materials are transferred to the work area, where they can be kept handy for quick access.

This is the memory, where the program under execution is stored temporarily, along with the required data under processing.

The knitter reads from the knitting pattern, one instruction at a time, and carries out the instruction, operating on the material at hand.

The knitter is the processor.

📖 Input and Output

Computing systems interact with the user and their surroundings through devices for input and output.

Input: data received by a system

Common Input Devices

 

Output: data transmitted from a system

Common Output Devices

📖 Activity 3 – Comprehension

Using the information above, complete the worksheet below.

 

Astronaut Tim Peake using an Astro Pi aboard the International Space Station.

📖 Plenary Activity – Wearable Computing

Google Glass is a wearable computing system. Use the worksheet below to label its components.

 

In this lesson, you…

  • Described the hardware components used in computing systems and how they work together in order to execute programs
  • Highlighted how all computing systems, regardless of form, are similar in structure (‘architecture’)

Next lesson, you will…

  • Explore how the processor, memory, and storage interact to execute programs in real scenarios
  • Define what an operating system is, and provide an overview of what it does

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