Module 1 Flashcards
It is a program (software) that acts
as an intermediary (interface)
between a user of a computer and
the computer hardware.
Operating System
It provides an
environment in
which a user
may execute
programs
Operating System
provides basic computing
resources (CPU,
memory, I/O devices)
Computer Hardware
Acts as an intermediary:
controls and coordinates
the use of the hardware
among the various
application programs for
the various users.
Examples: UNIX, LINUX,
WINDOWS, MS-DOS
Operating System
define the ways in which
the system resources are
used to solve the
computing problems of
the users (compilers,
database systems, video
games, business
programs)
System and Applications program
people, machines, other
computers
users
controls and coordinates the
use of the hardware among the various application
programs for the various users.
Operating System
provides basic computing resources
(CPU, memory, I/O devices).
Hardware
define the ways in which
the system resources are used to solve the
computing problems of the users (compilers,
database systems, video games, business
programs).
Applications programs
To provide a convenient environment, To use the computer hardware in an efficient manner (ensuring good
performance).
Operating System goals
manages and allocates
resources.
Resource allocator
controls the execution of
user programs and operations of I/O devices.
Control program
the one program running at all
times (all else being application programs)
Kernel
*Batch systems
* Multiprogrammed systems
* Time-sharing systems
Growth of Mainframe Systems
T/F First computers were used to tackle commercial and scientific applications
TRUE
T/F Physically enormous machines run from a console
T
card readers, tape drives
Input devices
card punch, tape drives, line printers
Output devices
- First rudimentary operating
system. - Reduce setup time by batching
similar jobs (that is jobs with
common needs are batched) - machine runs only one
application - Automatic job sequencing
automatically transfers control
from one job to another.
Batch Systems
a. Programmer
bring cards to
1401
b. 1401 reads
batch of jobs
onto tape
c. Operator
carries input
tape to 7094
d. 7094 does
the computing
e. Operator
carries output
tape to 1401
f. 1401 prints output
Early batch system
To ensure that the CPU is not
kept idle:
▪ Several jobs are kept in
main memory at the same
time; and
▪ The CPU is multiplexed
(partitioned) among them.
Multiprogrammed Batch Systems
some commands are executed from one
program, then that program is
suspended, and then some commands
are executed from the next program, and
so on
Multiprogramming
Allows the CPU to process
multiple programs
Multiprogramming
the system must choose among
several jobs to be brought into memory
Job scheduling
the system must
allocate the memory to several jobs
Memory management
the system must choose among
several jobs ready to run.
CPU scheduling
Allow many users to share one machine simultaneously
* The CPU is multiplexed among several jobs that are kept in
memory and on disk (the CPU is allocated to a job only if
the job is in memory).
* A job is swapped in and out of memory to the disk.
* On-line communication between the user and the system
is provided; when the operating system finishes the
execution of one command, it seeks the next “control
statement” from the user’s keyboard.
* On-line system must be available for users to access data
and code (instructions)
Time-Sharing Systems–Interactive Computing
*Can adopt technology developed for
larger operating system’ often
individuals have sole use of computer
and do not need advanced CPU
utilization of protection features.
* May run several different types of
operating systems (Windows, MacOS,
UNIX, Linux
Desktop Systems
computer system dedicated to a single user.
Personal computers
keyboards, mice,
display screens, small printers.
I/O devices
