Operating Systems

running on your Smartphone and PC

See too Computer Clocks (brief engineering notes) & VCU Virginia Commonwealth University Operating Systems Intro and Overview (archived)

  1. Android, first launched in 2008 by Google, is based on a modified version of the Linux kernel with many of its systems and applications subsequently written in Java, a language initiated by James Gosling in June 1991 while he was working for SUN Microsystems at Stanford in California.

    The Linux kernel was developed as an open-source operating system in 1991 and posted freely on USENet, a part of the Internet, by Linus Torvalds in Helsinki Finland.

    Linux was based on the UNIX operating system that employed the C programming language, written in 1971 for AT&T Telecommunications by Dennis Ritchie.

  2. iOS as employed on iPhones and iPads, also MacOS as employed on iMacs, both written in C.
  3. Windows 10 (in fact Windows fullstop) is written mostly in C.

    Click here for some of the background to C, the basis of so much hardware and software built during the past 50 years. When compiled, each C language program (with its list of English-like abbreviations and formulae) is converted to machine code under the control of the system clock, which provides timing services.

Browser programs are written mostly in C++
A Browser is different to an Operating System. It is a program (Chrome, Safari, Edge, IE, Firefox) on your computer designed to interpret web page commands. 



Web Pages are downloaded from Web Servers
Web Servers ALL send HTML and Javascript commands inside these web pages as a "Front End" to your local browser

Google Search Engine is a program running on its web servers. It is written in Python and C++ and Java

Bing Search Engine running on Microsoft's web servers is written in C++ and C#

Facebook uses PHP, Python, C++, Java, others
Youtube uses C, C++, Python, Java
Yahoo and Wikipedia and Wordpress use PHP
Amazon uses Java, C++, Perl
Whatsapp, purchased by Facebook in 2014, uses Erlang
WeChat is probably written in C or C++ or Java. Cloud Service is perhaps PHP

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