1.1 System Architecture

1.1 System Architecture

1. Hardware

   • The physical components of a computer

2. Software

   • Virtual programs that a computer can run

3. Input & Output Devices

   • Input - A device which transmits data into the computer.
   • Output - A device which presents the output to the user.

4. Von Neumann & Harvard

   • Neumann came up with the idea that programs and data could be stored in the same memory unit.
   • With Harvard, these were stored in separate memory units and entering or altering programs was harder.

5. CPU (Centural Processing Unit)

   • CU – Control Unit • Controls activities in the CPU (Such as flow of data between CPU and other parts) • Makes FDE cycle happens in order • Decodes instructions • Executes instructions
   • ALU – Arithmetic and Logic Unit • Performs logical operations (AND, OR, NOT) • Shift operations • Arithmetic operations (+,-, *, / )
   • Cache • Sits between the CPU and RAM. Very fast. Holds frequently used data so that the processor doesn’t have to keep going back and forth to the RAM.

6. FetchDecodeExicute Cycle

7. Factors that affect speed

   • Clock speed – Number of instructions that can be carried out in a second (Hz) – These days in Ghz (Billion)
   • Number of processor cores – Each core processes data independently of the rest. The more cores, the faster it can process. These days we have dual or quad cores but can have up to 6 or 8.
   • Cache size – A larger cache gives the CPU faster access to commonly used data. It is faster than RAM.

8. Special purpose CPU registers

   • Program Counter – Holds the memory address of the instruction for each cycle
   • Program Counter – Holds the memory address of the instruction for each cycle
   • MDR – Memory Data Register - Holds data or instructions that have been fetched from memory
   • Accumulator – Stores the results of the calculations done by the ALU

9. Embedded System

   • Embedded system – A computer system built into another device (usually designed for a specific purpose)