A Neutral Look at Operating Systems/DOS

Muggles' Guide to Harry Potter/Characters/Auntie Muriel

Introduction: what’s a DOS?[edit]

DOS, which stands for Disk Working System, is an OS that originally masses itself from disk. The boot PROM incorporates a trivial OS and a BIOS (primary enter/output system) that’s adequate solely to attain that preliminary load. (Earlier OSs loaded from paper tape, punched card or magnetic tape. The primary private computer systems, such because the Altair didn’t have an working system of any type though they could possibly be added later to make use of gadgets.)

In widespread with most different OSs, Disk Working Techniques consist of 4 major modules:

  • The prolonged enter/output system which reads and writes to disk and tape, reads from keyboard and writes to display screen and/or printer. (Therefore the time period “read-out” is a Hollywood nonsense neologism for “show”). Most DOSs are at the very least minimally open, in order that third social gathering builders can write {hardware} “drivers” (extensions to the I/O system) to assist their {hardware}. Mac OSs are essentially the most restrictive, Linux the least (absolutely open). Older Apple DOSs had been really pretty open.
    • The Community connection. (That is only a particular case of I/O however sometimes it’s helpful to deal with it individually.) No early OSs had networking (ignoring the trivial case of hooked up terminals), but it surely was added through the 1970 to 1990 interval.
  • The duty scheduler. Its perform is to find out which course of ought to run subsequent and for the way lengthy. In early OSs, this was pretty rudimentary – one activity had full management and if an utility crashed, the machine crashed. Interrupts had been used to present management again to the OS and a special course of takes over. A “grown up” OS wants pre-emptive multi-tasking, which got here to the mainframe world with Exec eight on Univac {hardware} in about 1970 and to the non-public laptop world in 1985 with AmigaOS.
  • The file (and listing) system
  • The Consumer Interface – in early OSs, that is only a command-line atmosphere.

All trendy OSs are disk working methods, however the time period “DOS” has caught to the primary technology private computer systems that used it.

Early proprietary DOSs[edit]

Well-known DOSs embrace PC-DOS/MS-DOS (Microsoft), DR-DOS (Digital Analysis), and FreeDOS. These are all designed to be suitable with MS-DOS. In reality to the typical laptop person MS-DOS is DOS. The remainder of this part discusses MS-DOS.
The title that Apple gave to DOS for the Apple II was initially DOS 3.1, which went to three.3, and was then utterly redone for ProDOS.


Right this moment, DOS is often utilized in embedded methods for low royalties, low reminiscence utilization, and ease of direct {hardware} entry. DOS stays fashionable amongst nostalgists, hobbyists, and in company/instructional environments the place a legacy runtime is required. Fairly merely, DOS provides compatibility with DOS packages that want complete management of the machine.


Foremost, there isn’t a built-in graphical interface for DOS, which may make it intimidating to learners.

Since DOS is with out a default GUI interface, the person should depend on first-party interfaces (Microsoft’s DOSSHELL and variations of Home windows from 1.03 to three.12) a non-standard Third-party interface (e.g. Gem/FreeGEM) or memorize easy methods to sort instructions to regulate DOS.

It’s broadly accepted that the command-line atmosphere that DOS supplies is inferior to the one offered by UNIX-like methods. One instance of that is that DOS methods lack a classy scripting atmosphere.

Along with a relatively restricted person interface, relative to any trendy OS, DOS has a number of different notable limitations, together with:

  • CPU and reminiscence utilization can’t be managed individually for a number of simultaneous processes (multitasking)
  • {hardware} invented after about 1995 – 1998 isn’t natively supported


Because the title suggests, FreeDOS is a free implementation of the MS-DOS working system. The mission was began in 1994 when Jim Corridor, a pupil on the College of Wisconsin – River Falls, was discouraged to listen to that Microsoft could be shifting away from their DOS working system with the discharge of Home windows 95.

For extra data, go to the FreeDOS web site at www.freedos.org.

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