Operating System Fundamentals and Early History
📌 An Operating System (OS) primarily manages computer resources (CPU, memory, I/O) for the user efficiently, reliably, and unobtrusively by providing clean abstractions over complex hardware.
💾 The concept of a "File" is an abstraction that hides the reality of data being scattered across storage; the OS handles gathering and ordering this data upon opening.
👨‍🔬 Early computing in the 1940s/50s was single-user, leading to massive waste until batch computing arrived in 1956 (GM Research Lab) to automate job loading/unloading.

Evolution Towards Concurrent Operation
🔄 The 1960s introduced multi-programming, enabled by hardware innovations like the Interrupt (UNIVAC 1103A) and increased memory, allowing one processor to run multiple programs concurrently while one utilized I/O.
🤝 Time-Sharing, proposed by John McCarthy in 1959, solved slow development times in batch systems by allowing many users to interact simultaneously via terminals, giving the illusion of dedicated use.
🖥️ MIT's CTSS (Compatible Time-Sharing System), prototyped in 1961 and announced in 1962, is considered the first time-sharing system expressly made for this purpose, supporting up to 30 users at once by 1965.

The Rise of Modern OS Concepts
🏛️ The ambitious Multics project (1964), a collaboration including Bell Labs and GE, aimed for a "computer utility" but ultimately failed commercially, though its ideas (security, hierarchical file systems) inspired successors.
👨‍💻 Unix, the spiritual successor to Multics, gained wide adoption because it incorporated revolutionary ideas like the pipeline and was written in the portable C programming language for minicomputers.
💾 The microcomputer era began with chips like the Intel 8080; Gary Kildall created CP/M (Control Program/Monitor), which became dominant for small systems, often functioning primarily as a Disk Operating System (DOS) managing floppy drives.

The Dominance of Microsoft and the PC Era
🛑 IBM’s secret PC project led them to Microsoft for an OS; Kildall's failure to personally meet IBM resulted in Microsoft licensing a system which they rebranded as MS-DOS.
📈 Microsoft licensed MS-DOS non-exclusively, allowing them to strike deals with PC clone makers, leading MS-DOS to overthrow CP/M and capture a fifth of the market by 1983.
🖼️ Windows, first released in late 1985 as a shell over MS-DOS, adopted the windowing Graphical User Interface (GUI), addressing the need for multitasking and easier command-line interaction.
💰 By 1993, Microsoft's Office suite bundled with Windows contributed 50% of the company’s revenues, cementing Microsoft's dominance in the 1990s PC universe.

The Mobile Revolution
📱 Early mobile devices like PDAs (e.g., Palm Pilot) were severely resource-constrained, leading operating systems like Windows CE (1996) to struggle due to poor battery life and stability issues.
📱 The Symbian OS, adopted by major phone makers like Nokia, reached a peak of 65% market share and one hundred million users but suffered from fragmentation and difficult development.
🍎 Apple’s iPhone breakthrough came from scaling down Mac OS X to create its OS, featuring a successful multi-touch interface, which was amplified by the App Store opening in 2008.
🌐 Google capitalized on this by pivoting their Linux-based Android OS to an open-source model, rapidly stealing share from closed systems like Symbian, making Android the world's most widely used OS today.

Key Points & Insights
➡️ The history of OS development shows a predictable progression: breakthroughs in compute enable feasibility, followed by memory improvements (DRAM/Floppy/Flash) for scaling, and finally, new interface paradigms (GUI, Multitouch) for interaction.
➡️ Early OS development was heavily constrained by hardware limitations (e.g., early PDAs running on 16 MHz processors and 128 KB RAM).
➡️ Microsoft’s crucial strategic move was licensing MS-DOS non-exclusively to IBM and subsequent OEMs, enabling exponential scale that CP/M's end-user licensing model could not match.
💡 The recent trajectory of LLMs—requiring compute breakthroughs, then memory scaling, and now new interaction paradigms (ChatGPT)—mirrors the historical cycle of Operating System evolution.

📸 Video summarized with SummaryTube.com on Dec 06, 2025, 15:07 UTC