Systems Architecture Keywords Fetch Execute Cycle Von Neumann Architecture, MAR (Memory Address Register), MDR (Memory Data Register), Program Counter, Accumulator, ALU (Arithmetic Logic Unit), CU (Control Unit), Cache, Fetch/Execute, Busses. Systems Architecture Fetch Execute Cycle

Internal CPU Diagram Objectives Diagram Answer: BEGINNER: Define CPU keywords and label an internal CPU diagram. ADVANCED: Describe and explain the MAR, MDR, Accumulator, ALU, CU, Cache and Program counter. EXPERT: Explain how the fetch-execute cycle works. Task: Define the keywords and then label the internal CPU diagram. Diagram Answer: PC MAR CIR MDR ALU Accumulator 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 INP Add 5 STO 8 ADD 8 Address Bus Data Bus Processor Main Memory Starter activity

Computer System Components Objectives BEGINNER: Describe the purpose and state the function of a CPU. ADVANCED: Explain common characteristics of a CPU and how they effect performance. EXPERT: State the purpose of embedded systems and give examples. Internal Parts The processor Main memory (RAM, ROM, EEPROM) I/O controllers Buses External Parts Starter activity Peripherals I/O Devices / I/O Ports Secondary Storage

Definitions Processor Objectives Main Memory - RAM BEGINNER: Describe the purpose and state the function of a CPU. ADVANCED: Explain common characteristics of a CPU and how they effect performance. EXPERT: State the purpose of embedded systems and give examples. Processor The “brains” of the computer Carries out instructions (Executes Instructions) Processes Data Retrieves Data/Instructions from Main Memory (Fetch) Stores Data into Main Memory once Executed Main Memory - RAM Starter activity Holds Data and Instructions that are currently in use by the processor Located on the Motherboard Directly Accessible by the processor All data/instructions are lost once power is turned off

Definitions Main Memory - ROM Objectives Main Memory - EEPROM BEGINNER: Describe the purpose and state the function of a CPU. ADVANCED: Explain common characteristics of a CPU and how they effect performance. EXPERT: State the purpose of embedded systems and give examples. Main Memory - ROM Instructions are permanently etched onto a ROM Chip When power is turned off – instructions still remain on the ROM chip. Bootstrap Loader is held in ROM Gives the instructions to start up the Operating System Main Memory - EEPROM Starter activity EEPROM – Electronically Erasable Programmable Read Only Memory E.g. Sim cards / Flash Memory Instructions/Data can be erased electronically and replaced

Definitions I/O Controllers Objectives System Busses BEGINNER: Describe the purpose and state the function of a CPU. ADVANCED: Explain common characteristics of a CPU and how they effect performance. EXPERT: State the purpose of embedded systems and give examples. I/O Controllers These are used to allow an interface between a hardware device external to the motherboard (e.g. a Keyboard) and the Processor itself. I/O controllers are used for: Keyboard, Mouse, Disk Drive, VDU System Busses Starter activity A bus is a set of parallel wires connecting two or more independent components of a computer system in order to pass signals between them. The System is split into three separate busses: The data bus The address bus The control bus

Definitions Address Bus Objectives Data Bus BEGINNER: Describe the purpose and state the function of a CPU. ADVANCED: Explain common characteristics of a CPU and how they effect performance. EXPERT: State the purpose of embedded systems and give examples. Address Bus Carries addresses from the Processor to main memory or other I/O devices It is one direction (Uni-Directional) The processor generates an address All data/Instructions are returned on the Data Bus Data Bus Starter activity Carries Data/Instructions from Main Memory to the Processor (or from other secondary storage devices) to the processor. Bi-Directional (two way) Data can be read/written

Definitions Control Bus Objectives Peripherals BEGINNER: Describe the purpose and state the function of a CPU. ADVANCED: Explain common characteristics of a CPU and how they effect performance. EXPERT: State the purpose of embedded systems and give examples. Control Bus Control signals are sent along the control bus E.g. Memory Read, Memory Write This instructs which was data will be travelling to/from memory. Peripherals Starter activity Peripherals are any devices that are not directly connected to the CPU E.g. mouse, keyboard, printer, hard disk drive, cd-rom drive These devices are known as I/O devices (Input/Output Devices)

Definitions I/O Ports Objectives Secondary Storage BEGINNER: Describe the purpose and state the function of a CPU. ADVANCED: Explain common characteristics of a CPU and how they effect performance. EXPERT: State the purpose of embedded systems and give examples. I/O Ports I/O Ports allow communication from an I/O device and the motherboard (hence CPU) Secondary Storage Starter activity Used for long term storage of data and instructions Hard Disk Drive Solid State Drive Flash Memory DVD-R Blu-ray

Fetch Objectives BEGINNER: Describe the purpose and state the function of a CPU. ADVANCED: Explain common characteristics of a CPU and how they effect performance. EXPERT: State the purpose of embedded systems and give examples. Program counter is incremented for each instruction of the program being executed The contents of the Program Counter are put into the MAR (Memory Address Register) The address is transferred along the Address Bus to Main Memory (this address indicates which part of memory to fetch the data/instructions from The data/instruction that has been addressed is transferred back to the processor along the data bus This is held in the Memory Data Register The instruction would then be transferred to the Current Instruction Register. Starter activity

Registers Objectives Program Counter Memory Address Register BEGINNER: Describe the purpose and state the function of a CPU. ADVANCED: Explain common characteristics of a CPU and how they effect performance. EXPERT: State the purpose of embedded systems and give examples. Program Counter Memory Address Register Holds the location of the next instruction/data address in Main Memory The contents of the PC are copied here and then transferred along the Address Bus Memory Data Register Current Instruction Register Once Data/Instructions are brought from the Memory Address in Main Memory – they are placed in the MDR. The instructions stored in the MDR are copied here Starter activity

Decode/Execute Objectives BEGINNER: Describe the purpose and state the function of a CPU. ADVANCED: Explain common characteristics of a CPU and how they effect performance. EXPERT: State the purpose of embedded systems and give examples. The instruction to be decoded is held in the Current Instruction Register The instruction is split into an Op-Code and an Operand The instruction is carried out by the ALU (Arithmetic Logic Unit) ALU Accumulator Control Unit Performs arithmetic and logical operations including +, -, AND, OR Results of calculations are placed into the Accumulator Sends Control Signals between the different internal components: Memory Read Memory Write Hard Disk Drive Read I/O Write Starter activity