Week_One_Revision

Week_One_Revision

1. Basic tasks a computer must do to function:

   • Input
     • obtaining raw data from the user/process
   • Process
     • performs functions on the data to turn it into information. This is handled by the processor.
   • Output
     • Displays this information into a readable format to the user.
   • Store
     • Storing the data, information or program code.  Usually stored on secondary disk drive NOT memory  

2. IPOS Cycle

3. What is an OS?

   • - It's a program that manages hardware and software. - Core component is the kernel (Linux).
   • It handles tasks such as:
     • Process Management
       • Carried out by the CPU. Controls what programs get allocated to the processor.
     • Memory Management
       • Usually uses the RAM memory. Controls what memory each program can use. Uses the memory hierachy to distribute memory to the most necessary processes and programs. 
     • Input/Output
       • Performs requests from programs for I/O actions. Abstracts details of how to interface with device(s). 
     • User Interface
   • How does it work?
     • - The user initiates requests.   - OS decides if user has access rights to perform requested actions and HOW to complete these actions.- Communication with devices is handled through device drivers. 

4. Main Functions of Kernel

   • The kernel is the core of the OS providing basic services to all other parts of the OS. It interacts with user commands. 
   • Processes:
     • Determines which processes are allowed to use the CPU.
   • Memory:
     • Keep track of memory usage -  What memory is allocated to each process? What memory is free?
   • Device Drivers:
     • The interface between hardware and processes.
   • System Calls:
     • Processes use system calls to communicate with the Kernel

5. Linux Shell

   • Linux shell is a user program or its tailorable environment provided for user interaction. The environment consists of previously defined terms and instructions.   It is a command interpreter that executes commands from input devices or files. It uses the Kernel to execute programs but is NOT part of the Kernel. 
   • Command Line - Interpreter
     • The interpreter is a program which is responsible for interpreting instructions.  It does this by translating each instruction on the command line into an executable statement.  
   • Compare and contrasts the GUI and CLI
     • Advantages of the GUI
       • - Less to learn and easier to control - Intuitive  - Allows for easy multitasking - Visual
       • Disadvantages of the GUI
         • - More time consuming for admin tasks such as file storage.  - Resource intensive for certain tasks and on hardware.
     • Advantages of the CLI
       • - Control - Speed  - Less resource intensive  - More is learnt/understood about the OS by using the CLI
       • Disadvantages of the CLI
         • - Harder to learn/use - Reduced speed if not sure what to do

6. What is the overall architecture of Linux and the Kernel

   • Linux architecture is a Modular System.  Everything that Linux DOES is a process. A process is a program the Kernel launches into memory to conduct a task. Process Manager = 1. Processes  2. Memory 

7. Virtual Machines

   • - A VM emulates a computer system. It's a combination of the software and data the captures the other platforms OS. - Host OS = The OS & hardware running the actual machine and VM. - Guest OS = The OS in controlled via the Virtual Machine Manager (VMM) which is running on the host OS.
   • VM Advantages: 1. Multi-Platform Expandable.2. Cost saving and scalable.3. Security. 4. Fewer physical resources required. 5. Remote access. 6. Gain administrative experience.
   • VM Disadvantages: 1. Virtual servers are expensive, however client software is often free. 2. VM software is processor and memory intensive.  3. Storage: Multiple VMs can used TB's worth of storage.   

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