Operating system: Difference between revisions

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History: To quote page 8 of the fifth edition of Tanenbaum and Bos, "All programming was done in absolute machine language, or even worse yet, by wiring up electrical circuits by connecting thousands of cables to plugboards to control the machine’s basic functions." This distinguishes between machine code and plugboards (and properly so - plugboards aren't machine code).
History: Not everything in POSIX is a "system call" in the sense of a call that makes a trap to kernel mode. Speak of APIs instead.
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The first computers in the late 1940s and 1950s were directly programmed either with [[plugboard]]s or with [[machine code]] inputted on media such as [[punch card]]s, without [[programming language]]s or operating systems.{{sfn|Tanenbaum|Bos|2023|p=8}} After the introduction of the [[transistor]] in the mid-1950s, [[mainframe]]s began to be built. These still needed professional operators{{sfn|Tanenbaum|Bos|2023|p=8}} but had rudimentary operating systems such as [[Fortran Monitor System]] (FMS) and [[IBSYS]].{{sfn|Tanenbaum|Bos|2023|p=10}} In the 1960s, [[IBM]] introduced the first series of intercompatible computers ([[System/360]]). All of them ran the same operating system—[[OS/360]]—which consisted of millions of lines of [[assembly language]] that had thousands of [[Software bug|bug]]s. The OS/360 also was the first popular operating system to support [[multiprogramming]], such that the CPU could be put to use on one job while another was waiting on [[input/output]] (I/O). Holding multiple jobs in [[memory (computing)|memory]] necessitated memory partitioning and safeguards against one job accessing the memory allocated to a different one.{{sfn|Tanenbaum|Bos|2023|pp=11–12}}
 
Around the same time, [[computer terminal|terminal]]s were invented so multiple users could access the computer simultaneously. The operating system [[MULTICS]] was intended to allow hundreds of users to access a large computer. Despite its limited adoption, it can be considered the precursor to [[cloud computing]]. The [[UNIX]] operating system originated as a development of MULTICS for a single user.{{sfn|Tanenbaum|Bos|2023|pp=13–14}} Because UNIX's [[source code]] was available, it became the basis of other, incompatible operating systems, of which the most successful were [[AT&T]]'s [[System V]] and the [[University of California]]'s [[Berkeley Software Distribution]] (BSD).{{sfn|Tanenbaum|Bos|2023|pp=14–15}} To increase compatibility, the [[IEEE]] released the [[POSIX]] standard for operating system calls[[application programming interface]]s (APIs), which is supported by most UNIX systems. [[MINIX]] was a stripped-down version of UNIX, developed in 1987 for educational uses, that inspired the commercially available, [[free software]] [[Linux]]. Since 2008, MINIX is used in controllers of most [[Intel]] [[microchips]], while Linux is widespread in [[data center]]s and [[Android (operating system)|Android]] smartphones.{{sfn|Tanenbaum|Bos|2023|p=15}}
===Microcomputers===
[[File:MS-Dos screenshot.png|thumb|[[Command-line interface]] of the [[MS-DOS]] operating system]]