COSC65

• Computer Architecture


  Those attributes of the system that are visible to the software programmer and have a direct impact on the logical execution of a program, like the number of bits used to represent various data types, the instruction set of the computer, technique for addressing memory, method used for input, output, etc.
• Main categories considered in computer architecture design

  • System Design
  • Instruction Set Architecture
  • Micro Architecture
• System Design


  Contains hardware components that are used for building the system
• Instruction Set Architecture


  Includes all the instructions provided to the computer system
• Micro Architecture


  Gives minute detail about storage element
• Computer Organization


  The way the various components of a computer system are interconnected and work together to perform tasks and execute programs
• 5 basic components of a computer

  • Input Unit
  • Output Unit
  • Memory Unit
  • Control Unit
  • Arithmetical and Logical Unit
• Input Unit


  Where commands are given to the device
• Output Unit


  Where the result of a command is displayed
• Memory Unit


  Stores the entered information and transmits it to other parts of the CPU
• Control Unit


  Manages the entire functioning of the computer device
• Arithmetical and Logical Unit


  Performs mathematical calculations and logical operations
• Instruction Set Architecture (ISA)


  Part of the abstract model of a computer that defines how the CPU is controlled by the software
• RISC Processor


  a microprocessor architecture with a simple collection and highly customized set of instructions, built to minimize the instruction execution time
• CISC Processorhas a large collection of complex instructions that range from simple to very complex and specialized, takes longer to execute instructions
• Types of Memory Hierarchy

  • External Memory/Secondary Memory
  • Internal Memory/Primary Memory
• External Memory/Secondary Memory

  • Hard Disk Drive (HDD)
  • Solid State Drive (SSD)
  • USB Flash Drive
  • External Hard Drive
  • Memory Card
  • NAS or File Servers
  • Cloud Storage
• Internal Memory/Primary Memory

  • Random Access Memory (RAM)
  • Cache Memory
  • Registers
  • Memory Controllers
  • On-Chip Memory (L1,L2, L3 Cache)
  • Non-volatile Memory (ROM)
• Registers

  • Program Counter (PC)
  • Instruction Register (IR)
  • Memory Address Register (MAR)
  • Memory Data Register (MDR)
  • Accumulator (ACC)
• Cache Memory


  Super-fast memory that stores frequently used data from main memory, located close to the CPU
• Cache Mapping

  • Direct Mapping
  • Associative Mapping
  • Set-Associative Mapping
• Types of Main Memory

  • Static RAM
  • Dynamic RAM
• Secondary Storage


  Non-volatile memory with larger storage capacity than main memory, includes HDDs and SSDs, slower access time than other memory types
• Design principles and trade-offs in memory hierarchy

  • Principle of Locality
  • Cost-Performance Trade-off
  • Caching
  • Block Size
  • Replacement Policy
  • Write Policy
• Pipelining


  Technique that allows a processor to execute multiple instructions at the same time by breaking them down into smaller steps
• Stages of Pipelining

  • Instruction Fetch
  • Instruction Decode
  • Instruction Execute
  • Memory Access
  • Write Back
• Types of Pipelines

  • Instruction pipeline
  • Arithmetic pipeline
• Benefits of Pipelining


  • Improves efficiency of processor by reducing idle time between instructions
• Challenges of Pipelining

  • Dependency problem
  • Branch problem
• Computer Organization


  It encompasses the design and arrangement of hardware components, including the central processing unit (CPU), memory, input/output devices, and control units, to ensure efficient and effective operation of the computer.
• Components of a Computer System


  Primary elements which make the functioning of an electronic device smooth and faster.
• Input Devices

  • Keyboard
  • Mouse
  • Scanner
  • Joystick
• Output Devices

  • Monitor
  • Speaker
  • Printer
  • Headphones
• Arithmetical and Logical Unit


  It can perform actions like a comparison of data and decision-making actions.
• Instruction Set Architecture


  acts as an interface between the hardware and the software, specifying both what the processor is capable of doing as well as how it gets done.
• Instruction Set Architecture 


  encompasses all the information necessary for programmers to write a machine language program that will run correctly, including instruction, register, memory access, I/O devices, etc.
• Instruction Set Architecture 


  allows computer designer to talk about the functions independently from the hardware that perform them.
• Three Parameters of RISC

  • Fetch
  • Decode
  • Execute
• Program Counter 


  Keeps track of the memory address of the next instruction to be fetched and executed.
• Instruction Register


  Holds the currently fetched instruction being executed by the CPU.