P2 T2 L2 The Operating System Flashcards
What is System software? (1 point)
- System software acts as an interface between the hardware of the computer and the application software that users need to run on the computer.
Explain the operating system (3 points)
- The operating system is designed to act as an interface between the user and the computer.
- It manages the overall operation of the computer.
- It links together hardware, the applications and the user but hides the complexity of the computer from the user and the other software – This is also called a virtual machine.
What are some of the tasks the OS performs? (7 things)
- Controls start-up configuration of your computer (placing icons, background…)
- Input recognition and processing (wiggling your mouse)
- Memory management (sending signals to hard disk controller, transferring memory, memory allocation i.e. allocating memory to programs in RAM, making sure they have enough memory to run)
- Error recovery (printer out of paper, CPU to hot)
- Shut down procedures
- Print queues
- Managing users on a network (controls who has access to what documents)
What is Resource Management? (2 points)
- A resource is “any object which can be allocated within a system” e.g. processors (CPUs), input/output devices, files, and memory (RAM).
- The operating system manages resources (resource allocation) and provides an interface to resources for application programs (resource abstraction).
Explain Resource Allocation (2 points)
- If a computer only needs to run a single program, then every resource can be allocated to that program but this is not very realistic as most computers run several programs at once.
- It is much more efficient for a computer to share its resources rather than dedicating all the resources to any single program until it finishes execution.
What is the scheduler? (1 point)
What are the different scheduling algorithms? (3 types)
The scheduler is the operating system module responsible for ensuring that processor time is used as efficiently as possible
There are different scheduling algorithms:
- Round Robin – each process in turn has use of the processor for a given time slice
- Shortest job next
- Priority system
What is scheduling? (2 points)
- Scheduling is a technique used to ensure different users or programs get access to different resources at the same time.
- The simplest way to allocate resources like the CPU is allocating time slices to different tasks.
How are inputs and outputs managed? (1 point)
- The OS controls how the input/output devices are allocated, controlled and used.
E.g.
Allocating print jobs to print queues
Sending power off request when power button pushed
Rendering windows, frames and dialogue boxes on the screen
Explain memory management (5 points)
- Memory management is the way files are stored on the primary memory.
- Memory management keeps track of each and every memory location either it is allocated to some process or it is free (in the heap).
- It checks how much memory is to be allocated to processes.
- It decides which process will get memory at what time.
- It tracks whenever some memory gets freed or unallocated and correspondingly it updates the status.
What is memory swapping? (1 point)
- Swapping is a mechanism in which a process can be swapped temporarily
out of main memory to a backing store, and then brought back into memory
for continued execution.
Explain virtual memory (6 steps)
- If your computer lacks the random access memory (RAM) needed to run a program or operation, Windows uses virtual memory to compensate.
- The idea of virtual memory is to create a virtual address space that doesn’t correspond to actual addresses in RAM.
- Virtual memory combines your computer’s RAM with temporary space on your hard disk.
- When RAM runs low, virtual memory moves data from RAM to a space called a paging file.
- Moving data to and from the paging file frees up RAM so your computer can complete its work.
- This process is called swapping.
What does the IO device management do? (3 things)
- Communicates with I/O devices via the I/O controller, part of the CPU
- Checks that a required output device is switched on and ready to receive data
- Deals with processor ‘interrupts’ (e.g. an “Out of paper” message from a printer)
(Backing store management)
The OS keeps track of where all files are stored on hard disk or external drives, and where space is free to be used if the user performs a ____ operation.
Files can be listed, moved, deleted, protected from unauthorised access.
save
