Computer Architecture Overview
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What happens to access time as you move down the memory hierarchy?

  • Access time fluctuates
  • Access time increases (correct)
  • Access time stays constant
  • Access time decreases

    • Which type of RAM is characterized by needing refreshing even when powered?

  • Static RAM
  • Read-Only Memory
  • Flash RAM
  • Dynamic RAM (correct)

    • What is the primary characteristic of static RAM compared to dynamic RAM?

  • Larger per bit size
  • Needs periodic refreshing
  • More complex construction (correct)
  • Slower access time

    • In the memory hierarchy, which memory type is the fastest?

    <p>Registers</p> Signup and view all the answers

    What is one advantage of dynamic RAM over static RAM?

    <p>Simpler and cheaper construction</p> Signup and view all the answers

    What is the average access time when there is a high percentage of Level 1 access?

    <p>Closer to Level 1 access time</p> Signup and view all the answers

    Which of the following memory types is considered to be non-volatile?

    <p>Disk</p> Signup and view all the answers

    What characteristic changes as you go down the memory hierarchy?

    <p>Decreasing frequency of access by the processor</p> Signup and view all the answers

    What is the main difference in ASCII character comparisons between Windows and Unix?

    <p>Windows comparisons are generally case insensitive.</p> Signup and view all the answers

    Which processors primarily use Little Endian format?

    <p>Intel processors</p> Signup and view all the answers

    For a bit map image with a resolution of 600 rows and 800 pixels, what is the total memory required if three bytes are used for each pixel?

    <p>1.5 MB</p> Signup and view all the answers

    What is the primary function of the control unit in the stored program concept?

    <p>To manage the execution of instructions and control data flow</p> Signup and view all the answers

    Which file format is an example of using Little Endian?

    <p>BMP</p> Signup and view all the answers

    What kind of images are characterized by continuous variations in shading, color, shape, and texture?

    <p>Bit Map Images</p> Signup and view all the answers

    What is the main advantage of the Harvard architecture over the von Neumann architecture?

    <p>It separates program memory and data memory for simultaneous access.</p> Signup and view all the answers

    Which component connects the four sub-components of the von Neumann architecture?

    <p>Bus</p> Signup and view all the answers

    Which compression technique can help reduce the size of bit map images?

    <p>Employing various compression algorithms</p> Signup and view all the answers

    Which of the following file formats can use either Big Endian or Little Endian encoding depending on specific codes?

    <p>TIFF</p> Signup and view all the answers

    What limitation does the von Neumann bottleneck impose on computer performance?

    <p>It restricts the speed of data transfer between the CPU and memory.</p> Signup and view all the answers

    In the context of the stored program concept, what does the 'fetch-execute' cycle entail?

    <p>Retrieving an instruction from memory and executing it in sequence.</p> Signup and view all the answers

    What is the primary characteristic of vector images?

    <p>Geometrical shapes and lines</p> Signup and view all the answers

    What characterizes the program memory in Harvard architecture?

    <p>It is read-only, preventing modifications by the program itself.</p> Signup and view all the answers

    What is one of the four key sub-components of the von Neumann architecture?

    <p>Input/Output</p> Signup and view all the answers

    Why is the stored program concept considered a significant paradigm shift in computing?

    <p>It permits both data and instructions to be stored in the same memory space.</p> Signup and view all the answers

    What does the address returned when a value is presented to the memory indicate?

    <p>Whether the value is stored in associative memory</p> Signup and view all the answers

    Which of the following best describes 'Write Through' policy?

    <p>Writes are sent to main memory and cache simultaneously</p> Signup and view all the answers

    What is a defining characteristic of a Hard Failure in semiconductor memory?

    <p>Permanent defect of a memory cell</p> Signup and view all the answers

    What does the Hamming error correcting code do when reading a stored word?

    <p>Checks the stored code to detect potential errors</p> Signup and view all the answers

    How do most computers represent data internally?

    <p>Using only binary digits</p> Signup and view all the answers

    What does the term 'bit' refer to in computer data organization?

    <p>A single binary digit</p> Signup and view all the answers

    Which statement accurately describes 'Write Back' policy?

    <p>Updates occur only in the cache until a replacement is necessary</p> Signup and view all the answers

    Which of the following is an example of a 'soft error'?

    <p>Data corruption due to power surges</p> Signup and view all the answers

    What does the process of digitizing an audio waveform typically involve?

    <p>Sampling an analog waveform at regular intervals</p> Signup and view all the answers

    What characterizes the WAVE audio format?

    <p>It supports both stereo and mono sound</p> Signup and view all the answers

    In the digitizing process of audio, which of the following statements is true about the A-to-D conversion?

    <p>It sets the most positive peak to the maximum binary number</p> Signup and view all the answers

    How is a character, such as 'T', sent from the keyboard to the computer?

    <p>The signal is first converted to its ASCII binary code</p> Signup and view all the answers

    Which of the following best describes data compression?

    <p>Encoding only the most important features of audio</p> Signup and view all the answers

    What is an essential characteristic of the MP3 audio format?

    <p>It is a popular method of data compression</p> Signup and view all the answers

    What role do interrupt handlers play in input-output organization?

    <p>They help manage and execute I/O operations efficiently</p> Signup and view all the answers

    Which of the following methods is NOT considered a way to perform I/O operations?

    <p>Parallel processing</p> Signup and view all the answers

    Study Notes

    Von Neumann Architecture

    • Introduced the stored program concept, where instructions are stored in memory alongside data.
    • This revolutionized computing and remains the fundamental architecture used today.
    • Consists of four sub-components: Memory, Input/Output (IO), Arithmetic-Logic Unit (ALU), and Control Unit.
    • A fifth crucial component, the bus, connects these components and facilitates data transfer between them.
    • The fetch-execute cycle governs the process of moving information through these sub-components.

    Von Neumann Bottleneck

    • Occurs due to the shared bus between program memory and data memory.
    • This shared bus limits data transfer rate (throughput) between the CPU and memory.
    • Results in slower processing speed when the CPU needs to process large amounts of data.

    Harvard Architecture

    • Named after the Harvard Mark I computer, which used relays.
    • Features physically separated signals and storage for program and data memory.
    • Allows simultaneous access to both program memory and data memory.
    • Program memory is read-only, while data memory is read-write.
    • Prevents programs from modifying their own instructions.

    Memory Types

    • Semiconductor: RAM (Random Access Memory)
    • Magnetic: Disk and Tape
    • Optical: CD and DVD
    • Others: Bubble and Hologram

    Memory Hierarchy

    • Registers

    • L1 Cache

    • L2 Cache

    • Main Memory

    • Disk Cache

    • Disk

    • Optical

    • Tape

    • Moving down the hierarchy:

      • Decreases cost per bit.
      • Increases capacity.
      • Increases access time.
      • Decreases frequency of access by the processor.

    Semiconductor Memory

    • Each memory cell exists in one of two states.
    • Allows read/write operations.

    RAM (Random Access Memory)

    • All semiconductor memory is technically random access, but the term "RAM" is used specifically for this type.
    • Allows both read and write operations.
    • Volatile, meaning data is lost when power is removed.
    • Provides temporary storage.
    • Two types: Static RAM (SRAM) and Dynamic RAM (DRAM).

    Dynamic RAM (DRAM)

    • Stores bits as charges in capacitors.
    • Requires refreshing because charges leak.
    • Simpler construction.
    • Smaller per bit size.
    • Less expensive.
    • Requires refresh circuits.
    • Slower.
    • Primarily used for main memory.

    Static RAM (SRAM)

    • Stores bits as on/off switches.
    • No charge leakage, so no refresh needed.
    • More complex construction.
    • Larger per bit size.
    • More expensive.
    • Does not require refresh circuits.
    • Faster.
    • Typically used as cache memory.

    DRAM Organization

    • A 16 Mbit chip can be organized as 1M of 16-bit words.
    • A bit per chip system uses 16 1Mbit chips to store each bit of a word.
    • A 16 Mbit chip can be organized as a 2048 x 2048 x 4-bit array.
    • Multiplexing row and column addresses reduces the number of address pins.

    Associative Memory

    • Stores data in a key-value pair format.
    • When a value is presented, the address of that value is returned if it exists.
    • If not, an indication of its absence is returned.
    • Comparisons are done simultaneously, making searches very fast.
    • Expensive to implement

    Write Policy (For Caches)

    • Ensures main memory is up to date before overwriting a cache block.
    • Multiple CPUs can have individual caches.
    • I/O can directly address main memory.

    Write-Through

    • All writes are performed in both the cache and main memory.
    • Allows multiple CPUs to monitor main memory traffic and keep their caches up to date.
    • Generates a lot of traffic, slowing down writes.

    Write-Back

    • Updates are initially made only in the cache.
    • An update bit is set in the cache slot for each update.
    • When a block needs to be replaced, it's only written back to main memory if the update bit is set.
    • Leads to potential cache inconsistencies between different CPUs.
    • I/O operations must access main memory through the cache.
    • Only about 15% of memory references involve writes.

    Error Correction

    • Semiconductor memory can experience errors.

    Hard Failure

    • Permanent defect in a memory cell.

    Soft Error

    • Caused by power supply issues or external radiation.
    • Random and non-destructive.
    • No permanent damage to memory.
    • Detected using Hamming error-correcting codes.

    Error-Correcting Code Function

    • When data is to be written into memory, a code is generated based on the data using a calculation.
    • This code is stored along with the data.
    • When reading data, the stored code is used to detect and potentially correct errors.
    • Hamming error-correction codes are commonly used.

    Data Representation

    • Computers handle various types of information:

      • Numeric
      • Characters
      • Visual
      • Audio

    • All data is represented as numbers for processing by a computer.

    • Most computers are digital, recognizing only two states: on or off.

    Bits, Bytes, and Words

    • Information is stored as groups of binary digits (bits).
    • Eight bits form a byte.
    • Bytes are grouped into words.

    ASCII (American Standard Code for Information Interchange)

    • A standard character encoding scheme.
    • Each character is represented by a unique 7-bit code.
    • Allows computers to compare and sort characters alphabetically.

    EBCDIC (Extended Binary Coded Decimal Interchange Code)

    • Another character encoding standard mainly used by IBM mainframe systems.
    • Uses 8-bit codes to represent characters.

    Unicode

    • A 16-bit character encoding standard.
    • Encodes over 65,000 characters, supporting most languages.
    • Uses scripts to define characters for specific languages.

    Big Endian vs Little Endian

    • Data is often stored using multiple bytes.
    • Endianness refers to how these bytes are arranged in memory:
      • Big Endian: Most significant byte is stored first (high memory address).
      • Little Endian: Least significant byte is stored first (low memory address).

    Image Formats

    • Two main categories:
      • Bitmap: Images are created by storing data for individual pixels (e.g., photographs).
      • Vector: Images are created as a collection of geometric shapes and lines (e.g., illustrations).

    Bit Map Images

    • Stored as an array of pixel data.
    • Each pixel typically uses multiple bytes to represent color information.
    • Can be compressed using various algorithms.

    Vector Graphics

    • Defined by a series of objects such as lines and circles.
    • Can be scaled and manipulated without losing quality.
    • Often use PostScript or SVG formats.

    Audio Data

    • Digitizing audio involves sampling the analog waveform at regular intervals and converting the amplitude at each interval to a binary value.

    Wave (.WAV) Sound Format

    • A simple audio format designed by Microsoft.
    • Supports 8 or 16-bit sound samples, various sample rates, stereo or mono.
    • Real Audio and MP3 are widely used for compressing audio files, resulting in smaller file sizes.

    Data Representation: Keyboard Input

    • When a key is pressed on the keyboard:
      • An electronic signal is sent to the system unit.
      • The signal is converted to its ASCII binary code.
      • The binary code is stored in memory for processing.
      • After processing, the code is converted back to an image on the output device.

    Input/Output (I/O) Organization

    • Computers interact with the outside world through the I/O subsystem.
    • This subsystem consists of:
      • Ports (connections for peripherals).
      • Buses (data paths for communication).
      • Devices (peripherals like keyboards, monitors, etc.).
      • Controllers (manage device operations).

    I/O Software

    • Provides software support for I/O operations:
      • Interrupt Handlers: Respond to events from I/O devices.
      • Device Drivers: Manage specific types of I/O devices.
      • Device-Independent Software: Provides a common interface for interacting with different I/O devices.
      • User-Space I/O Software: Allows applications to use I/O devices.

    I/O Operation Methods

    • Three main methods:
      • Polling: The CPU continuously checks the status of I/O devices.
      • Interrupt: I/O devices interrupt the CPU when they are ready.
      • Direct Memory Access (DMA): Allows I/O devices to directly access memory without CPU intervention.

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    Description

    Explore the fundamentals of computer architecture including the Von Neumann and Harvard architectures. Understand the stored program concept, the fetch-execute cycle, and the implications of the Von Neumann bottleneck. This quiz will enhance your knowledge of how computers process information and the structural differences among various architectures.

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