OPERATING SYSTEM
The operating system is the most important program that runs
on a computer. Every general-purpose computer must have an operating system to
run other programs and applications. Operating systems perform basic tasks,
such as recognizing input from keyboard, sending output to the display screen,
keeping track of files and directories on the disk, and controlling peripheral
devices such as disk drives and printers.
For large systems, the operating system has even
greaterresponsibilities and powers. It is like traffic cop – it makes sure that
different programs and users running at the same time do not interfere with
each other. The operating system is also responsible for securit, ensuring that
unauthorized users do not access the system.
There are some categories of operating system :
- Multi-user : Allows two ro more users to run programs at the same time.
- Multi-processing : Supports running a program on more than one CPU.
- Multi-tasking : Allows more than one program to run concurrently.
- Multi-threading : Allows different parts of a single program to run concurrently
- Real-time : Responds to input instantly. Genera-purpose operating systems, such as DOS and UNIX, are not real-time.
OPEN SOURCE
Open Source Software is computer software with its source
code made available with a license in which the copyright holder provides the
rights to study, change and distribute the software to anyone and for any
purpose. Open Source Software is often developed in a publice, collaborative
manner. Open Source Software is most prominent example of open-source
development and oftem compared to (technically defined) user-generated content
or (legally defined) open-content movements.
CLOSE SOURCE
Closed Source (or proprietary) is a type of computer program
source code development. With closed source software, the source code is not
shared with the public for anyone to look at or make changes to. Closed source
is the opposite of open source. Consider a software platform as a threshold,
you can go to higher levels of abstraction and use APIs, libraries and code
native but if you can’t go and edit the way the language or program does
something due to fact that the code is not available or you are not allowed
legally then that’s closed source.
BIT and BYTE
Bit (short for binary digit) is the smallest unit of data in
a computer. A bit has a single binary value, either 0 or 1. Although computers
usually provide instructions that can test and manipulate bits, they generally
are designed to store data and execute instructions. While Byte is abbreviation
of binary term, a unit of storage capable of holding a single character, is
formed from 8 digit of bit. Next, is how to calculate bit to byte
1 bit = 1 or 0
1 byte = 8 bits
1 kilobytes =
1024 bytes
1 megabytes = 1024
kilobytes
1 gigabytes =
1024 megabytes
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