Please enable JavaScript.

Coggle requires JavaScript to display documents.

Computer science (1.1.3 (ROM stores bootstrap (boot up instructions, OS…

- - - - sends control signals on control bus
    - - transfers signals between internal components
      - System buses
        
        control
        
        data
        
        address
    - - performs basic logic operations and arithmetic
    - - accumulators
      - MDR
      - MAR
      - CIR
      - PC
- - - - OS PROVIDES
      - UI
      - memory management
      - interrupt handling
      - scheduling
      - divides memory into fixed size pages. Programs given necessary pages
      - words are variable size
      - interrupts are looked for at the end of a clock cycle
        
        interrupts handled in order of priority
        
        less important interrupts put in "LAST IN FIRST OUT" stacks
      - Scheduling done to provide acceptable response time and fairness to all users
      - ROUND ROBIN: FIFO, each job given time SLICE to use COM resources
      - First come first served: job executed until done. Can hold up processor's resources if job is large e.g printing a page.
      - Shortest remaining time: Job w/ shortest time to completion executed
    - - Disk defragmenter
      - Auto update/backup
      - Antivirus
        
        behaviour of files compared to that of known viruses
      - compression
    - - Distributed OS
        
        coordinates processing of single job across multiple COMPs
        
        access more processor power with what seems like 1 processor
      - Multitasking OS
        
        A COM that takes advantage of scheduling
      - multi-user OS
        
        users on terminals access a mainframe, each get a time slice
      - embedded OS
        
        minimal features, apps held in ROM, UI=simple
      - Real Time OS
        
        responds in a guaranteed amount of time
        
        has fail safes
      - BIOS
        
        boots computer, initialises & tests hardware
        
        loads OS to RAM
    - - Libraries allow programs to use pre-written routines
      - translators translate code to executable code
    - - General purpose
        
        performs multiple tasks
      - Special purpose
        
        performs a single task
      - Bespoke
        
        program designed specifically for certain hardware
        
        more expensive, used by businesses
      - Off-the shelf
        
        available to the public
      - Open source
        
        usually free, anybody can modify and sell, if sold must be open source
      - Closed Source
        
        payed for, must have license, source code can not be seen