CPU Architecture Quiz

CPU Architecture

• The Central Processing Unit (CPU) is the brain of a computer, responsible for carrying out instructions and performing operations.
• The CPU consists of three main components:
  • Arithmetic Logic Unit (ALU): Performs arithmetic operations like addition, subtraction, multiplication, and division. It also handles logical operations like AND, OR, NOT, and comparisons.
  • Control Unit (CU): Manages the flow of instructions and data within the CPU. It decodes instructions, fetches data from memory, and directs the ALU to execute operations.
  • Registers: Small, high-speed memory units within the CPU used to store temporary data and instructions.
• Key registers within the CPU:
  • Memory Address Register (MAR): Holds the address of the next instruction or data to be fetched from memory. It communicates with the address bus.
  • Memory Data Register (MDR): Stores the data that is fetched from or sent to memory. It connects to the data bus.

Buses

• Buses are physical pathways that transfer electronic signals between components within the computer.
• Three types of buses:
  • Control Bus: Transmits instructions from the CU to registers and the ALU.
  • Address Bus: Transmits addresses where instructions and data are located.
  • Data Bus: Carries data to and from the memory.

Memory

• Primary Memory (RAM):
  • Volatile, meaning data is lost when power is turned off.
  • Accessed directly by the CPU, providing fast data transfer.
  • Further divided into DRAM (Dynamic RAM) and SRAM (Static RAM).
  • Used as temporary storage for the operating system, running programs and other data.
• Read Only Memory (ROM):
  • Non-volatile, meaning data persists even when power is off.
  • Stores instructions and data that don't change, like the BIOS, which controls the boot process.
• Cache Memory:
  • Small, very fast memory that stores frequently accessed data from main memory.
  • Reduces average memory access times, speeding up processing.
  • Works by checking the cache first for requested data.
    • If the data is found (cache-hit), the CPU retrieves it quickly.
    • if not found (cache-miss), the CPU goes to main memory to fetch it, which is slower.

Machine Instruction Cycle

• The CPU executes instructions in a cyclic process called the machine instruction cycle.
• Four steps:
  • Fetch: The CPU fetches the next instruction from memory, storing it in the Instruction Register (IR). The program counter (PC) holds the address of the next instruction.
  • Decode: The Control Unit decodes the instruction to understand what operation to perform.
  • Execute: The ALU carries out the instruction. This might involve reading data from memory, performing calculations, or writing data back to memory.
  • Store: The results of the executed instruction are stored back in memory.

Persistent Storage

• Persistent storage refers to storage devices that retain data even when the power is turned off.
• Examples:
  • Solid State Drives (SSD): Direct access storage, faster than HDDs, with medium capacity.
  • Hard Disk Drives (HDD): Magnetic storage, large capacity, but slower than SSDs.
  • USB Memory Sticks: Solid state storage, medium capacity.
  • Digital Versatile Disks (DVD): Optical storage, medium capacity.
  • Blu-ray: Optical storage, higher capacity than DVD.
  • Magnetic Tape: Sequential access storage, large capacity, used for backups.

Storage Units

• Byte: 1 byte is the smallest unit of storage.
• Kilobyte (KB): 1 KB = 1024 bytes.
• Megabyte (MB): 1 MB = 1024 KB.
• Gigabyte (GB): 1 GB = 1024 MB.
• Terabyte (TB): 1 TB = 1024 GB.
• Petabyte (PB): 1 PB = 1024 TB.
• Exabyte (EB): 1 EB = 1024 PB.

Operating System (OS)

• The operating system is system software that manages the computer's hardware and provides a platform for application software to run.
• It acts as an intermediary between the user and the hardware.
• Key functions:
  • Memory Management:
    • Allocates memory for programs and data.
    • Protects programs from each other.
    • Reclaims and allocates memory as needed.
    • Manages virtual memory.
  • File Management:
    • Manages the loading and saving of files to secondary storage.
    • Organizes files into a logical hierarchy using folders and directories.
    • Hides physical storage locations from the user (abstraction).
  • Scheduling:
    • Determines which task to execute next.
    • Aims to:
      • Optimize CPU usage, minimizing idle time.
      • Efficiently utilize resources (e.g., printer, secondary storage).
      • Maximize task completion or user support.
      • Provide quick response times for users.
  • Utilities: Provides various tools for managing the system, like disk defragmentation, drive formatting, backup, and print spooling.

Scheduling Algorithms

• Round Robin (Time-Slicing): Allocates equal time slices to each task in turn. Tasks that don't finish within their time slice go to the back of the queue. Priorities can be used to prioritize certain tasks.
• Shortest Job First: Prioritizes tasks with the shortest estimated completion times, aiming to finish more jobs quickly.

Data Representation

• ASCII: A standard character encoding system that uses 7 bits to represent 128 unique characters.
• Unicode: A more extensive encoding system, using up to 32 bits to represent a wider array of characters from different languages.

Images

• Images are represented using pixels, with each pixel defined by a group of binary digits (bits).
• The number of bits per pixel determines image quality and resolution.
• Bit-mapped Images: Composed of a grid of pixels.
• Each pixel's color is represented using 3 bytes (24 bits) for red, green, and blue components (RGB).
• Each component can have a value between 0 (minimum) and 255 (maximum).
• Full Color: Offers 256 cubed (16.7 million) different colors from 000000 (black) to FFFFFF (white).

Sound

• The quality and size of a sound file depend on factors like sampling rate, bit depth, and duration.
• Sampling Rate: Determines how many times per second the audio signal is measured (samples per second).
• Bit Depth: Determines the number of bits used to represent each sample, impacting the dynamic range and fidelity of the sound.
• Stereo Sound: Two channels (left and right) to create a more immersive listening experience.
• Higher sampling rates and bit depths result in higher quality but larger file sizes.

Test your knowledge on CPU architecture with this quiz. Explore the components of the CPU, including the Arithmetic Logic Unit, Control Unit, and various registers. Assess your understanding of how these parts function together to execute instructions.