Unit 1.1 Systems Architecture

Unit 1.1 Systems Architecture

1. Computer Components

   • CPU
     • Main component within a computer
     • Location of the fetch-decode-execute cycle
   • MAR
     • Memory Address Register
     • Contains the address of the instruction next to be or previously executed
   • MDR
     • Memory Data Register
     • Also known as the MBR (Memory Buffer Register)
     • Contains the data to be stored in the computer's storage
   • CIR
     • Current Instruction Register
     • Part of the CPU
     • Holds the instruction currently being executed
   • ALU
     • Arithmetic Logic Unit
     • A combinational, digital, electronic circuit
     • Performs arithmetic operations on integer binary numbers
   • CU
     • Control Unit
     • Directs the operation of the processor
     • Part of the CPU
   • PC
     • Program Counter
     • Register in the CPU
     • As instructions are fetched, its count increases respectivelly
     • Contains the address of the instruction currently being executed
   • Accumulator
     • In the CPU
     • Stores intermediate arithmetic and logic results

2. RAM + ROM

   • See Unit 1.2 Mind Map

3. Computational Speeds

   • Computer speeds are measured in hertz (Hz)
   • 1 GHz can perform 1 billion instructions per second
   • Computer speeds can be affected by Cores
   • A dual-core processor may be able to perform up to twice the amount of instructions per second

4. Cache

   • Smallest but fastest form of memory
   • Can speed up a computer
   • Contains frequently used instructions (due to close proximity to CPU)

5. Secondary Storage

   • An external device containing extra storage space for a computer
   • Includes Memory Sticks, CD/DVDs, External Hard Drives and SD Cards

6. Embedded Systems

   • Made up of hardware and software
   • Built into another device
   • They do not rely upon an OS
   • Used to provide specific, pre-defined functions