Computer Science

Computer Science

1. MEMORY

   • R.O.M
     • Read.Only.Memory
     • does not require power to maintain the contents and is non-volatile
     • is often used to store the boot program
     • cannot be overwritten by the computer, hence Read Only Memory
     • does not need to contain very much data and is typically just 1 or 2MB in size
   • R.A.M
     • Random.Access.Memory
       • Two types of RAM
         • Dynamic RAM
           • can only hold a charge for a few milliseconds and must be constantly refreshed
         • Static RAM
           • does not need to be constantly refreshed, but is a much more complex and expensive design
     • is memory that can be accessed/changed by the computer at any time
     • The operating system will also be loaded into RAM in order to run
     • needs power to store data and is volatile
   • Virtual memory
     • is part of the hard drive used as an extension to the RAM
     • It is used when the computer does not have enough RAM to hold all the data and programs that a user wants
     • A specific area of the hard drive will be allocated to temporarily store data from RAM that is currently not needed, while data that is needed will be loaded into RAM

2. VOLATILE

   • is computer memory that requires power to maintain the stored information

3. FLASH MEMORY

   • a kind of memory that retains data in the absence of a power supply

4. SOFTWARE

   • An algorithm that is coded for a computer to use to perform tasks is a program
   • Programs are generally known as software, to distinguish them from the hardware on which they run
   • Software is written using programming languages, a type of software
   • are many types of software but they generally fall into three main categories
     • Systems software
       • Systems software includes:
         • Operating systems
           • Device drivers
             • Firmware
               • Servers
                 • Utilities
                   • Interfaces
       • Multi-tasking allows the computer to make best use of the CPU
       • The CPU works much faster than RAM and the other components of the computer.
       • While the CPU waits for other actions to complete, e.g. loading data to RAM, it works on other tasks
       • A multi-tasking operating system allows several processes to be in RAM at the same time
         • Running:
           • The CPU is currently dealing with this process and others must wait.
         • Runnable:
           • These are ready to go and just need the running program to finish or be interrupted to get the CPU’s attention so they can run.
         • Waiting:
           • these processes are waiting to get into the queue and become runnable.
     • Applications
     • Development software

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