Written on 3rd January, 2023, Published on 12th January, 2023
What is an Operating System?
An operating system is any software that runs on kernel mode. The operating system provides an abstraction of the hardware to application programmers and application programs. The OS also manages the resources of the computer, these resources includes printers, mice, keywords, processes which are all part of the modern computer. It usually serves as the software that controls other software on top of it running at user mode.
Most modern machines have two modes of operation, the Kernel / Supervisor mode and the User Mode. The OS, which sits right on top of the machine’s hardware interface, runs in the kernel mode. This allows it to execute any instruction that the machine is capable of. All other programs run in the User Mode where some fundamental instructions of the machine are forbidden.
I can’t define operating systems without talking about the generations of computers. I will list down the generations below but I will only write about the Operation Systems from the 4th generation of computers as that is the generation of operating system that I intend to build through out these write ups.
Generations of Computing Machines
First Generation ( 1945 - 55 ) - Vacuum Tubes
Professor John Atanasoff and Clifford Berry built what is now regarded as the first functioning digital computer. It used 300 vacuum tubes. In this generation of computers, all programming was done in machine language. Machine language is a lower level language than even assembly language. Machine language is peculiar to any given machine. That is, two different computing machines had two different machine languages, and usually, they were not portable. To program any machine, the programmer had to learn its specific machine language.
The Second Generation ( 1955 - 65 ): Transistors and Batch Systems
The invention of the transistor set in the new wave of computers. Computers could now be manufactured at a comparatively cheaper price. They were slightly more reliable too. They worked for longer periods of time. They were sold mainly to institutions such as businesses, governments, and universities) to help with number crunching. These machines were called mainframes.
The Third Generation ( 1965 - 1980 ): ICs and Multiprogramming
The IBM 360 was the first major computer line to adopt this tech. It was at this generation of computers that Unix was built.
The Fourth Generation Personal Computers ( 1980 - Present ): Personal Computers
The microprocessor chip made it possible for individuals to own personal computers.
In 1974 Intel built the first general purpose 8-bit CPU and wanted an operating system. Gary Kildall was contacted to write one. Gary would later take this OS from Intel and create the world’s dominant OS company at the time. Before there was Windows and Macintosh.
In the early 1980’s IBM designed the IBM PC. They reached out to Gary Kildall considering that he had already written an IOs for the intel 8080, to write the PC’s operating system but failed to make a deal with him. They reached a deal with Bill Gates though, who in turn bought an OS from Tim Paterson and the rest is history. [ This part of the story is very shortened since it is long story on it own. ] I would urge the curious reader to look into the story as I have provided a link above as a start. In 2016 after learning about this, I actually added the story to a book that I was writting at the time. The book is lying in a box now 2 rooms away from me as I type this. I hope to publish it one day.
You see in the early days operating systems didn’t have fancy graphics, Operations were based on users typing in commands into the computer from a hooked keyboard. More like what we call terminal or CLI or MS DOS in windows. In the 1960s Doug Engelbert, the inventor of the mouse at Stanford Research Institute made a demo later termed the mother of all demos. It launched the Graphical User Interface era.
These ideas were incorporated into OS design by researchers at Xerox PARC where both Steve Jobs and Bill Gates saw their implementations and copied them into their respective OSs. The Windows OS and the Apple Macintosh.
x86
The OS I am trying to build is going to be based on the x86 architecture. The x86 architecture refers to all modern processors that are based on the instruction set architecture that started with the intel 8086 in the 1970s.
There are several such processes that are been manufactured by companies including AMD and Intel, these processes may vary is various aspects, they could be 32-bit or 64-bit but fundamentally they are the same and code that was written based on the x86 decades ago can still work on recent processors.
GUI
A few paragraphs above,I mentioned that operating systems used not the to have shinny graphics until Doug Engelbert invented the GUI, that said the operating system that I am trying to build doesn’t come with a GUI.Before GUI the most used formed of UI was a Text UI. A Text UI is a User Interface where all the output is in the form of Text. Text UI is easy to implement so I will be implementing one for the OS. Most Operating Systems derived from Unix support a windowing system called the X Window System produced at MIT, this windowing system provides basic window management functions. Usually A full GUI like Gnome or KDE can be run on top of the X Window System. Ubuntu uses Gnome and Unity and some Unix Derivatives use KDE. For about 10 years, from 1985 - 1995, Windows was just a GUI on top of MS-DOS.
The Fifth Generation ( 1990 - Present ): Mobile Computers
I hope this gives you a better view and understanding of what an OS really is and What I am trying to build. Later write ups will give more details on my progress.
Thanks to Yaw for proofreading this piece and suggesting some edits. Really Grateful