System software 1.2.1 Flashcards
What is meant by an Operating system(OS)?
Software that manages computers, and allows humans to use them.
Describe the features of Operating system.
Held in permanent memory
Loaded by the Basic Input Output System (BIOS)
Manages the computer’s hardware.
What are the five roles of an operating system?
Memory management
Interrupt service routines
Processor scheduling
Backing store management
Input / Output management
What is meant by backing store management?
Allocating addresses in secondary memory.
Modifying and deleting data in secondary memory.
Describe the function of a driver?
Allow a computer system to interface with new hardware.
What is meant by memory management?
Allocating, tracking, and deleting data on primary memory.
What is physical location?
A register on a hardware device.
What is logical location?
A position in an algorithm or process.
Describe the functions of paging?
Memory is divided into 4Kb sections.
Processes can be stored across several pages.
Pages can be loaded / dumped as needed.
What is meant by segmentation?
Dividing memory logically according to program needs.
Describe the functions of segmentation?
Memory is divided into sections of variable length.
Sections can be loaded individually.
What is meant by an interrupt?
A signal to the CPU to change the process it is completing.
Describe the process of interrupt?
Interrupt signal received.
Stores values of registers for current task.
Completes interrupt service routine.
Restores previous task.
Examples of interrupts?
Power failure
Clock (scheduled) interrupt
Input / Output requests
Define Processor scheduling?
Assigning different tasks to a CPU at different times to give the appearance of multi-tasking.
What are the 5 examples of processor scheduling?
First come First Served
Shortest Remaining Time
Shortest Job First
Round robin
Multi-level feedback queues
What is the basic input output system(BIOS)?
Initialises system hardware and loads the operating system.
Communicates hardware errors
Describe the functions of a Multi Tasking System?
Runs on a standalone computer. Performs multiple tasks at the same time. e.g. Windows 10
Describe the functions of a multi-user multi tasking system?
A single powerful computer connected to multiple terminals. Each user gets a slice of CPU time.
Describe the functions of a distributed operating system?
A parallel processing system that performs tasks across multiple computers and servers, but appears to the user as a single interface.
e.g. The school network
It allows each device to do what it does best.
Describe the function of a real-time operating system?
An OS that responds very quickly to inputs. Deals with many inputs simultaneously. Incorporates redundancy.
It must not stop even if there’s an error.
What is meant by an Embedded Operating Systems?
An OS built into another device.
What are the features of an Embedded Operating Systems?
Usually very simple.
Limited RAM, little if any secondary storage.
Few inputs / outputs.
What is meant by a virtual machine?
Software that imitates an operating system on another machine.
State the uses of virtual machine.
Use a portion of the real operating system’s resources.
Test suspicious software / files.
Test software in specific environments.
