OPERATING SYSTEMS LESSON 1 Flashcards
What is an Operating System
A software that goes in between the applications that run on a computer and its hardware.
3 Components of a Computer System
Peopleware, Software, Hardware
The people involved in the data processing operation
Peopleware
The visible components that make up the computer system.
Hardware
A program or series of instructions that allows the computer to run efficiently, including programming languages, application programs and the computer system
Software
To the UserView
OS is an extended machine that hides the lower level details
To the SystemView
It serves as a resource allocator
Component of limited availability necessary for effective operation
Resource
A manager that needs to use all the resources to perform management duties
Operating System
A device software that regulates and manages machine resources
Operating System
10 Broad functions of the OS are the following
JOB SEQUENCING
JOB CONTROL LANGUAGE INTERPRETATION
ERROR HANDLING
I/O HANDLING
INTERRUPT HANDLING
SCHEDULING
RESOURCE CONTROL
PROTECTION
MULTI-ACCESS (TIME SHARING)
– the selection of the next batch of processes for a long job to be run.
Job Sequencing
- the OS activity that detects errors and in some cases corrects errors
Error Handling
- a command language used to with a batch operating system
JCL (Job Control Language Interpretation)
- a program that causes the automatic suspension of a program concurrently executing
Interrupt Handling
determining the order by which resources will be assigned to processes and
jobs.
Scheduling
– the control of the resource used by two or more processes, either
concurrently or one at a time.
Resource Control
the process of controlling and limiting access to the resources of the
computer.
Protection
– a type of OS that switches inactive to a certain computer for
multiple user’s using the system at the same time.
Multi Access (Time sharing)
(OS viewed) – allocating resources like printers, disk drives and other peripherals.
Resource Manager
(6) An operating system can be viewed as:
RESOURCE MANAGER
INTERFACE
COORDINATOR
GUARDIAN
RESOURCE UTILIZATION MAXIMIZER
ACCOUNTANT
SERVER
INTERFACE
(OS viewed) - It provides a friendlier environment where user can do things at a “higher level” and not have to worry about low level hardware operations.
Interface
(OS viewed) - – it makes it possible for complex activities to be performed in a predefined order.
Coordinator
(OS viewed) it set up access controls to protect files, allows restrictions on the reading, writing or executing of data and programs and keep users out of each other’s hair and out of its own. It may even control who can log onto the system.
Guardian
(OS viewed) – An OS, combining some user’s input, others’ database accesses, others’ computation, others’ output and so on can automatically increase the utilization resources. A typical estimate is that going from one user to 4 or 5 can increase the utilization from 30-90%.
Resource Utilization Maximizer
(OS viewed) – it keeps track of CPU time, memory usage, I/O calls, disk storage, terminal connects, and time and almost any other information you might want to have.
Accountant
(OS viewed) it provides services either implicitly or explicitly. A fundamentally important example of this is the file access mechanism. In most high level languages, it is so easy to specify a file access that we tend to forget all that is actually being done.
Server
is an operating system that has a multi-user and multitasking capabilities, device
independence and what is known as the tools approach that UNIX users can produce more.
UNIX OPERATING SYSTEM
NAME 4 OF UNIX’S features
MULTI-USER CAPABILITIES
MULTITASKING CAPABILITIES
DEVICE INDEPENDENCE
PORTABILITY AND OPEN SYSTEM
(UNIX) each of the computer’s users can be involved in
completely unrelated tasks while seemingly holding the computer’s undivided
attention.
Multi-user Capabilities
(UNIX) UNIX continuously decides who to work with next and how long to
spend with each user. It also offers the following advantages such as cost per user,
central administration and shared resources.
Multi-user Capabilities
(UNIX) For each user, it may perform more than one task at a
time, thereby increasing their efficiency
Multitasking Capabilities