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• What is an embedded system?

  Computers built into other devices,
• Examples of embedded systems.

  Dishwashers, Microwaves and Oven
• How many tasks can an embedded system do?

  Dedicated to a single task.
• What is the CPU?

  Central processing unit that processes all of the data and instructions.
• What are the characteristics of a CPU?

  - Clock Speed

  - Number of cores

  - Cache size
• What is the CPU architecture called?

  Von Neumann
• What are the three main parts of a CPU?

  - Control Unit (CU)

  - Arithmetic Logic Unit(ALU)

  - Cache
• What is the program counter(PC)?

  Holds the memory address of the instructions for each cycle.
• What is memory address register(MAR)?


  Holds any memory address about to be used by the CPU.
• What is the Accumulator?


  Stores intermediate results of calculations in the ALU.
• What is memory data register(MAR)?


  Holds the real data or instructions.
• What is the CPU cycle called?

  Fetch-Decode-Execute cycle.
• What is cache memory?

  Temporary storage for frequently accessed data.
• How does cache size memory improve performance?


  It is closer to the CPU than RAM, which can provide data and instructions to the CPU at a faster rate.
• What is clock speed?

  Measure of how quickly a CPU can process instructions.
• What is Clock speed measured in?

  Hertz(Hz)
• What does it mean if a computer has a clock of 3.5 GHz?

  It can perform 3.5 billion cycles a second.
• How does clock speed improve the performance?

  The faster the clock speed, the faster the computer can perform the FDE cycle.
• How does a number of cores improve performance?

  A single core processor can execute one instruction at a time, whereas a dual-core processor can execute multiple instructions at a time.
• Primary storage


  -Very quick

  - Directly accessed by the CPU

  - smaller in storage size
• Secondary storage

  - Slower as it is not directly accessed by the CPU

  - Larger in storage size

  - Long-term storage
• What is volatile storage/memory?

  temporary data is, lost whenever the power is turned off. e.g. RAM
• What is non-volatile storage/memory?

  Saves the data even when not being powered. e.g. ROM
• Why do computers need primary storage?

  Access speed is much faster than secondary storage which allows the program instructions and data to be copied at a faster rate.
• What is RAM? Is it volatile or non volatile?

  RAM is volatile memory storage that stores all programs that are currently running.
• What is ROM? Is it volatile or non volatile?


  ROM is non-volatile memory that stores the boot program/BIOS for a computer to start.
• What is virtual memory?

  When RAM is full the computer then uses secondary storage as an extension of RAM.
• Registers


  Fast/high-speed memory within the CPU, used by the processor to store small pieces of information e.g. current instruction, next instruction, and result of calculation
• Registers


  • MAR
  • MDR
  • ACC
  • PC
• MAR (memory address register)


  Holds the address of the current instruction that is to be fetched or stored
• MDR (memory data register)


  Holds the data or instruction that has been fetched from memory or is to be sent to memory
• ACC (accumulator)


  Stores the results of the CPU calculations (logical or mathematical)
• PC (program counter)


  Holds the address of the next instruction to be fetched
• Von Neumann architecture


  • Design of storing both program instructions and data in the same memory (RAM)
• Program and data are stored in memory
• Fetch, decode, execute cycle

  1. Fetch instruction from main memory

  2. PC is increased by 1

  3. The memory address displayed to the PC is copied into MAR

  4. The instruction stored in the MAR is copied to the MDR

  5. Decode instruction

  6. CPU is prepared for the next cycle

  7. The instruction in the MDR is decoded by the CU

  8. The CU may prepare for the next step by loading values into the MAR or MOR

  9. Execute instruction

  10. The result of the decoded instruction is executed

  11. Any result of an execution is stored in the Acc

  12. Repeat
• PC


  Program Counter
• MAR


  Memory Address Register
• MDR


  Memory Data Register
• CU


  Control Unit