Kinds of operating systems

Nowadays there exist 2 kinds of operating systems, UNIX like and Windows. Of course there are others but they are either discontinued (say AmigaOS), or just not relevant.

UNIX

UNIX is an operating system originally developed by AT&T in 1970 at Bell Laboratories, with a team consisting of Ken Thompson, Dennis Ritchie and others. A UNIX operating system is usually written in C and C ++ (with some pieces of Assembly) and consists of the following components:

• Kernel: The kernel is the central part of the operating system, it is the first thing that runs when you turn on the computer, handles processes, filesystems, allows you to access the network, run programs. It has tools and drivers that allow you to use the keyboard, screen, mouse, etc .... It should be noted that this is not the operating system.

• System Programs and Applications: They are what allows you to use the system, which makes it useful since without them the system is nothing. Actually there is a difference between a program and an application. A program is needed to run the system (ex. bash) and an application is something that helps us do something useful (ex. Microsoft Office).

• C Library: Unlike with other OS's, the C Library is essential for any UNIX system to work. We will define what it is later in the documentation.

• Other Utilities: Although this fit better in the System Programs and Applications section, I have decided to give them a special section since must UNIX like systems feature some suite of Utilities (either GNU's or BSD's) which are essential programs to use the system. Examples of this Utilities are a shell (usually bash), Binutils, GCC, etc...

It should be noted that today UNIX is not only an operating system, but a family of operating systems, each with a kernel and sometimes different programs, but all work in the same way. This factor was started in the 70's when AT&T, allowed the use of UNIX under a license to certain educational institutions and trade marks such as: University of California, Berkeley (BSD), Microsoft (Xenix, nothing to do with Windows), IBM (AIX) and Sun Microsystems (Solaris). Finally, in the early 1990s, AT & T sold UNIX rights, which ended up in The Open Group, which allows the use of certified UNIX if certain requirements are met. But not all UNIX systems are official and certified, there are clones like Linux. Examples of today's UNIX-like operating systems are Oracle Solaris, macOS (darwin), FreeBSD, NetBSD, Linux (a clone of Unix), Android (based on Linux), HP-UX, IOS, etc ... Unix is also ​​not limited to the use of computers, but can also be used in phones, clocks, gaming consoles, drones, etc ... Besides all this, it is also very good in network management and for programmers due to their compatibility and portability; it is also multi-user and multi-tasking operating system. It also features a permission system that prevents unauthorized persons to read, write or execute files or applications (depending on the permissions that are being used). UNIX is also o¡open source.

Screenshot of bash in a UNIX System

Windows

Windows actually started as the GUI of a whole other operating system called MS-DOS. MS-DOS was an operating system originally developed by Seattle Computer Products (as 86-DOS, a clone of CP/M for the x86 architecture), then acquired by Microsoft in 1981 because of a request from IBM for a new operating system for its new range of personal computers. Microsoft bought the rights for version 1.10 for $75,000 and made some modifications to comply with IBM's specification and renamed the operating system to MS-DOS but kept the version number. IBM licensed it and released as PC DOS 1.0 in 1981 for use in their personal computers. For the first few years Microsoft developed both versions of DOS, and they were the same product just with different names. But then Microsoft stopped developing PC-DOS leaving IBM to do it, and because of this the products became 2 entirely different products. MS-DOS used a Monolithic Kernel, was single user and was not multi-tasking (only v.4.0 featured multi-tasking). The default user interface was a command line where the user typed in commands in order to tell the computer what to do. Some of the commands were:

cd: Used to change directories.
chdir: Used to change directories as well.
dir: Used to show the contents of one or more directories.
attrib: Display and change file attributes.
cls: Clear the screen.
color: Change the background color of the command line.
comp: Used to compare files.
compact: Compress and uncompress files and directories.
copy: Copy a file from one place to another.
date: View and change the system date.
mkdir: Create a directory.

DOS prompt example.

This is were Windows came in as a GUI for MS-DOS.