Architecture

• components:

  • input
  • output
  • memory
  • control
  • datapath

• concepts:

  • Design Principles:
    1. Simplicity favors regularity
    2. Smaller is faster
    3. Good design demands good compromises
  • stored-program concept is the idea that instructions and data of many types can be stored in memory as numbers, leading to the stored-program computer

• todo

  • memory hierarchy
  • cache memory
  • virtual memory
  • I/O devices
  • system-on-chip (SoC)
  • control unit
  • operands
  • program counter (PC) (aka instruction pointer (IP) in x86)
  • instruction register (IR)
  • pipelining
  • physical address space
  • address space
  • memory-mapped I/O (MMIO)
  • port-mapped I/O (PMIO)
  • bus
    • address bus
    • data bus
    • control bus

• arithmetic logic unit (ALU)

• general-purpose register (GPR)

• instruction set architecture (ISA) (or architecture) is an abstract interface between the hardware and the lowest-level software that encompasses all the information necessary to write a machine language program that will run correctly, including instructions, registers, memory access, I/O, and so on

  • RISC (reduced instruction set computer)
    • RISC-V is an open-source ISA based on established RISC principles
    • Examples:
      • MIPS
      • ARM
  • CISC (complex instruction set computer)
    • Examples:
      • x86
      • PowerPC

• a word The natural unit of access in a computer; the word size (or word length) is the number of bits in a word

  • word size may be used for:
    • registers: the number of bits in a general-purpose register
    • memory addresses: the number of bits in a memory address
    • instructions
    • data types (e.g., integer, floating-point, character)
    • address bus
    • data bus
  • e.g., 32 bits in MIPS, 64 bits in x86-64, or 16 bits in the 8086

• register is a small, fast storage location within the CPU used to store data temporarily

  • register file
  • The process of putting less commonly used variables (or those needed later) into memory is called spilling registers

• endianess is the order in which bytes are stored in memory

  • big-endian: the most significant byte is stored at the smallest memory address
    • Example: 0x12345678 is stored as 0x12 0x34 0x56 0x78
  • little-endian: the least significant byte is stored at the smallest memory address
    • Example: 0x12345678 is stored as 0x78 0x56 0x34 0x12

Memory

• main memory (or (primary) memory or RAM (random access memory))
  • volatile (loses data when power is off)

  • DRAM (dynamic random access memory)

  • SRAM (static random access memory)
• secondary storage (or secondary memory or storage)
  • nonvolatile (retains data even when power is off)
  • types:
    • magnetic storage
      • magnetic tape
      • hard disk drive (HDD)
      • floppy disk drive (FDD)
    • optical storage
      • compact disc (CD)
      • digital versatile disc (DVD)
      • Blu-ray disc
    • Solid-state storage (SSS)
      • flash memory - nonvolatile semiconductor memory
        • solid-state drive (SSD)
        • USB flash drive
        • memory card
      • memory card
        • SD card
        • microSD card