104 votes
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Does "Disk Operating System" imply that there was a "non-disk" Operating System?

The term "Disk Operating System", or commonly "DOS", was used in the early days of personal computing to distinguish operating systems that also contained software for supporting disk devices, since ...
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90 votes

What key factor led to the sudden commercial success of MS Windows with v3.0?

There were a number of factors involved. Windows 3.0 introduced a more refined user interface than available in Windows 2.0: more colours, proportional fonts everywhere, smaller icons, and MDI ...
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88 votes
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What key factor led to the sudden commercial success of MS Windows with v3.0?

Stephen Kitt covers the bases well, but I think the majority of the reason relates to fact that Windows 3.0 finally brought 286 protected mode execution to the masses. Even though the 80286 was first ...
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84 votes
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Why did Windows 95 crash the whole system but newer Windows only crashed programs?

You are comparing apples to motorcycles. Windows 95 traces its lineage back through Windows 3.x all the way to Windows 1.x and MS-DOS/PC-DOS, themselves inspired by CP/M. It was conceived and ...
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  • 5,036
79 votes

Does "Disk Operating System" imply that there was a "non-disk" Operating System?

It doesn't imply that it's the disk operating system so much as it implies that it's the disk-operating system. You could boot an Apple II from ROM, enter and run BASIC programs, load programs from ...
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76 votes
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Were later MS-DOS versions still implemented in x86 assembly?

C did exist when DOS was developed, but it wasn’t used much outside the Unix world, and as mentioned by JdeBP, wouldn’t necessarily have been considered a good language for systems programming on ...
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74 votes
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How exactly did Windows become the OS of the home PC?

The short version is that Windows became the de facto operating system thanks to Microsoft’s business acumen (or shenanigans, depending on your point of view), marketing, skilled developers, a strong ...
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69 votes
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Why was BASIC built into so many operating systems?

Having a programming language built-in gave you a multi-purpose tool into your hands at the flick of a switch (power on). As to the choice of BASIC vs. other programming languages, microcomputer ...
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63 votes
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How should we interpret Dave Cutler's criticism of Unix?

The I/O model on "Cutler systems" – RSX-11M, VAX/VMS, Windows NT – is an asynchronous packet-driven I/O model, rather than the fundamentally synchronous I/O model of Unix. At its core, you ...
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57 votes
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What was the first operating system called DOS?

DOS/360 (As distinct from TOS/360, the tape OS) Announced at the end of 1964 per Wikipedia.
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  • 28.3k
54 votes
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Which original retrocomputer OS's are still maintained and updated today, for original hardware?

My previous research into retrocomputer OS updates has led me to the following list. For each retrocomputer OS, the date and version of the latest update released at time of posting is included. The ...
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46 votes

Why was BASIC built into so many operating systems?

Having BASIC available for the machine was a selling point so early adopters wouldn't have to wait for software to become available--they could write what they need themselves, and they wouldn't need ...
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45 votes

Does "Disk Operating System" imply that there was a "non-disk" Operating System?

The term DOS pre-dates the personal computer by a looong way: the term DOS/360 was first coined by IBM in 1964 as a new operating system for their System/360 mainframe computers, to replace TOS (tape ...
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  • 551
42 votes
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What was the first operating system to be called an "operating system"?

As is often the case, a candidate for the first system to be described by its authors as an “operating system” is the Atlas supervisor, described in the eponymous paper published in December 1961, ...
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39 votes

Why was BASIC built into so many operating systems?

Nobody so far has said the magic words, which is Microsoft BASIC. First developed for the Altair 8800 (the first commercially successful personal computer!), Microsoft spent a lot of energy making ...
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  • 493
39 votes

Why did Windows 95 crash the whole system but newer Windows only crashed programs?

The decision about whether to kill a process or crash the OS generally depends on whether the problem can be isolated to the process. For example, if a running process in user mode attempts to read ...
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  • 28.3k
38 votes

Processor and operating systems for automatic lifts/elevators

If I need to be more specific about the meaning of 'intelligence' then I'm happy to restrict this to the first use of one or other elevator algorithms All the algorithms mentioned in that post have ...
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35 votes

Were later MS-DOS versions still implemented in x86 assembly?

From The OS/2 Museum page about DOS3: "The new ATTRIB.EXE utility allowed the user to manipulate file attributes (Read-only, Hidden, System, etc.). It is notable for being the first DOS utility ...
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33 votes
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Where does the hierarchical directory structure originate from?

The first hierarchical system capable of supporting arbitrary directory structures was designed for Multics, which pre-dates Unix. It is described in A General-Purpose File System For Secondary ...
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33 votes

Late 1970s and 6502 chip facilities for operating systems

The simple answer is that early operating systems for the systems you mention did not provide those features. Apple DOS, for example, makes no use of interrupts, and has no concept of processes or ...
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  • 9,956
32 votes

How exactly did Windows become the OS of the home PC?

The other answers include a lot of sound historical information about how Windows evolved into its dominant role on PC's in both the home and business environment. But I think the most fundamental, ...
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31 votes
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What was the first operating system to feature a separate kernel?

Reading through Per Brinch Hansen's The evolution of operating systems paper, I get the impression the two main candidates for operating systems with identifiably separate kernels are Dijkstra's THE ...
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  • 96.6k
31 votes

Were later MS-DOS versions still implemented in x86 assembly?

MS-DOS (by which I mean the underlying IO.SYS and MSDOS.SYS files) was written in assembly through the first half of the 1990s. In 1995 for Windows 95, which was bootstrapped by what you would call ...
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  • 411
31 votes
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What was this OS / Application on a 80286?

Since the computer was a gift from your aunt, working for IBM, the screen split in four reminds me immediately of the IBM PS/1’s “4-quadrant” interface: (The screenshot above is from IBMulator, an ...
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  • 96.6k
30 votes

Why was preemptive multitasking so slow in coming to consumer OS's?

Memory protection. It's not that preemptive multi-tasking is expensive, or hard. It's not. It's easy. It costs (or can cost) essentially the same as cooperative multitasking. You have to save process ...
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29 votes
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The origins of fork()

The fork() system call is definitely older than the C language because it already existed in the UNIX v0 draft, page 18 of the PDF, when the C language hasn't been conceived yet. The mechanism was ...
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  • 16.4k
29 votes
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Late 1970s and 6502 chip facilities for operating systems

For "home" computer systems such as the Apple II, the "operating system" wasn't anything like a modern one with processes and device drivers and so on; by the standards of modern ...
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  • 21.9k
28 votes
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Why the DOS extender and DPMI were unavailable to DOS programs on 286 standard mode of Windows 3.0

TL;DR: on 286s in standard-mode Windows, DOS programs run one at a time in real mode, with Windows suspended, so the restrictions of enhanced mode which rendered DPMI necessary don’t apply. The “trick”...
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  • 96.6k
27 votes
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What is most appropriate choice for DOS for a 1990 80386 PC?

If you’re going for strict historical accuracy, a 1990 PC could have had either MS-DOS/PC-DOS 3.3, MS-DOS/PC-DOS 4.01, or DR DOS 5, along with Windows 3.0. MS-DOS 5 was released in 1991, and DR DOS 6 ...
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