Von Neumann Architecture and Embedded Systems

This page covers the Von Neumann architecture and introduces the concept of embedded systems.

Von Neumann Architecture

The Von Neumann architecture, also known as the stored program concept, is a fundamental principle in computer design.

Definition: The stored program concept is the idea that both instructions and data can be stored together in the same memory.

Key components of the Von Neumann architecture include:

• Input device
• Central Processing Unit (CPU)
  • Control unit
  • Arithmetic logic unit
  • Registers
• Memory unit
• Output device

Embedded Systems

Definition: An embedded system is a computer system with a dedicated function within a larger mechanical or electrical system.

Characteristics of embedded systems:

• Built into a specific device or appliance
• Designed for a particular task
• Often have real-time computing constraints

Example: A microwave timer is an example of an embedded system.

Uses of Embedded Systems:

• Monitoring and controlling various components in devices and machines
• Providing specific functionality within a larger system

Highlight: Embedded systems are ubiquitous in modern technology, found in everything from household appliances to industrial machinery.

Review Questions on Computer Hardware

This page provides a set of review questions to test understanding of the concepts covered in the previous sections.

1. According to the von Neumann architecture, state the two items held in RAM.

2. Describe how data is stored on optical media.

3. Identify the type of secondary storage that stores data as electric charges.

4. Name the hardware component that carries instructions from memory to the CPU.

5. Explain why a higher clock speed within a CPU is desirable.

6. Identify a bus that is unidirectional.

7. Describe how an embedded system using a sensor could control car windscreen wipers.

8. Explain the method of data storage on magnetic media.

9. Detail the roles of the control unit, control bus, data bus, and address bus in fetching an instruction from memory.

10. Specify the type of main memory used to store a computer's startup process.

Highlight: These questions cover a range of topics including memory types, storage methods, CPU components, and embedded systems. They are designed to reinforce key concepts and test comprehension of the material covered in this computer hardware revision notes pdf.

Example: For question 7, consider how a rain sensor could detect moisture and signal the embedded system to activate the wipers at an appropriate speed.

Vocabulary: Terms like "unidirectional" (question 6) refer to data flow in one direction only, which is important in understanding bus types in computer architecture.

Hardware Components and Concepts

This page introduces fundamental hardware components and concepts in computer systems.

What is Hardware? Hardware refers to the physical components that make up a computer system. These tangible parts work together to enable the functioning of a computer.

Types of Memory

Read-Only Memory (ROM):

• Non-volatile memory that retains data when power is off
• Stores boot sequences and BIOS $Basic Input/Output System$

Definition: ROM is a type of computer memory that can only be read from, not written to. It retains its contents even when the power is turned off.

Random Access Memory (RAM):

• Volatile memory that loses data when power is off
• Stores currently running programs and frequently used data
• Includes cache for most used programs

Example: The operating system software is typically loaded into RAM when the computer starts up.

Registers:

• Very fast memory used for temporary data storage within the CPU

Storage Types

Magnetic Storage:

• Uses different types of magnetization to represent data
• Magnetized points indicate '1', demagnetized points indicate '0'
• Examples: Hard drives, floppy disks, cassette tapes

Solid State Storage:

• Uses electric current to move electrons
• Data is represented by the arrangement of these electrons
• Examples: USB drives, MicroSD cards, SSDs (Solid State Drives)

Optical Storage:

• Uses patterns of marks on a surface
• A laser detects pits to read data ('1' for a pit, '0' for no pit)
• Examples: CDs, DVDs, Blu-ray discs

CPU Components and Functions

Fetch-Decode-Execute Cycle:

1. Fetch: CPU retrieves instructions from RAM
2. Decode: CPU interprets instructions into recognizable commands
3. Execute: CPU carries out the commands

Control Unit:

• Executes instructions and controls data flow

Arithmetic Logic Unit (ALU):

• Performs calculations and logical operations

Data Transfer Components

Data Bus:

• Carries the actual data being transferred

Address Bus:

• Contains the location information for data

Control Bus:

• Sends control signals to manage data flow

Highlight: Understanding these hardware components and their functions is crucial for grasping how computers process and store information.