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Ch11-15 Computer Systems, image, image, image, Which one works faster? CPU…

- - - - Processing power determined by:
        
        number of cores (e.g. 2 to 18): 1 core = 1 processor, more cores > more efficient
        
        clock speed/rate (e.g. 3.9, 4.5, 5.0 GHz): Hertz = 1 clock cycle per second, high clock speed > high performance
        
        word length/size (e.g. 64 bit): amount of data handled by CPU at one time
        
        cache memory (e.g. 8 MB, 12 MB): smaller, faster memory, located close to processor, stores frequently used data by the main memory, more cache > more efficient (Level 1 to 4)
      - Purpose: to execute program instructions (brain of a computer)
      - Components
        
        ALU (Arithmetic & Logic Unit)
        
        CU (Control Unit)
        
        Registers:
        
        Control Register
        
        Instruction Register (IR)
        
        Program Counter (PC)
        
        Memory Address Register (MAR)
        
        Memory Data Register (MDR)
        
        Status Register (SR)
      - System buses
        
        Data bus - transfer data and instructions
        Address bus - transfer memory address data
        Control bus - transfer control signals
    - - RAM
        (Random Access Memory)
        
        Purpose: temporarily stores data and program to be executed by CPU
        
        Volatile: keep data only when power is on
        
        Performance depends on:
        
        storage capacities: 8 GB, 16 GB, 32 GB
        
        clock speed: e.g. 3733 MHz, 4267 MHz
        
        type of module: DDR3, DDR4
        
        access time (nanosecond)
      - ROM (Read-only Memory)
        
        Purpose: stores crucial programs (firmware) for booting up and operate a computer
        
        Non-volatile: keep data even when power is off
        
        Types:
        EPROM (Erasable programmable read-only memory)
        EEPROM (Electrically erasable programmable read-only memory): used in flash memory
    - - Fetch
        Decode
        Execute
- - - - bulky, consumes more power, produces radiation
    - - light, thin, consume less power, no radiation
  - - - slow, noisy, low quality output, but good for producing carbon copies
    - - slow, quiet, high quality output, printer low cost, high running cost due to expensive ink
    - - fast, quiet, high quality output, low running cost
    - - commonly used in supermarkets, thermal paper print out will faint over time
    - - printing large maps, banners, posters
- - - - Internal
        External
- - - - Classic DOS game (Prince of Persia)
        https://www.retrogames.cz/play_102-DOS.php?language=EN
  - - - single-user vs multi-user (UNIX)
      - open-source (Linux) vs commercial (Windows, MacOS)
        
        Creative commons
    - - Anti-virus
        
        detects and remove computer virus
        
        virus information stored in definition file or dictionary
        
        possible actions: remove virus, delete infected file, quarantee infected file
        
        Which type of virus is the most destructive?
      - Backup utility
        
        make copies of selected files which can be later restored to hard disk
        
        backup all files requires long time > incremental backup (backup modified files only)
        
        Do you backup your data? Why and why not? What kind of data should be backup?
      - Disk defragmenter
        
        re-organized scattered data on hard disk in contiguous locations
        
        reduce data access time
        
        To reduce access time, which one is more effective? Defragmenter or SSD?
      - File recovery
        
        recover corrupted or accidentally deleted files
        
        useful for non-backup files and files deleted in trash can
        
        Becoming less popular nowadays? Why?
      - System monitoring
        
        monitor system performance, CPU usage, main memory usage
      - File compression
        
        one or more files compressed to single file with smaller file size
        
        save time in sending data through network and open by receiver
        
        e.g. Winzip, WinRAR
      - OS Update
        
        bugs fix
        
        add new functions
        
        improve performance
- - - - https://youtu.be/f3cx4PGDGmg
        https://youtu.be/4TUrsRvKZOc
        World fastest supercomputer
        
        Japan's Fugaku
        
        computational speed: 442 petaflops
        
        1 petaflop = 10^5 floating point operations / sec
    - - RAID storage
        
        data are copied (mirrored) across multiple hard disks
        
        provides fault tolerant storage
  - - - Real-time flight tracker
        https://flightaware.com/
  - - - scale up at same location
        
        Supercomputer
      - scale up at different locations
        
        Distributed processing system
        
        similar to parallel processing system in concept, but only the computers or CPUs are in different locations connected by a network
        
        advantage: fault tolerant, easily expandable
        
        e.g. massively multiplayer on-line game