Beginning in the mid-1970s, a new class of small computers came onto the marketplace. Featuring 8-bit processors, typically the MOS Technology 6502,Intel 8080, Motorola 6800 or the Zilog Z80, along with rudimentary input and output interfaces and as much RAM as practical, these systems started out as kit-based hobbyist computers but soon evolved into an essential business tool.
Home computers
While many eight-bit home computers of the 1980s, such as the BBC Micro,Commodore 64, Apple II series, the Atari 8-bit, the Amstrad CPC, ZX Spectrumseries and others could load a third-party disk-loading operating system, such as CP/M or GEOS, they were generally used without one. Their built-in operating systems were designed in an era when floppy disk drives were very expensive and not expected to be used by most users, so the standard storage device on most was a tape drive using standard compact cassettes. Most, if not all, of these computers shipped with a built-in BASIC interpreter on ROM, which also served as a crude command line interface, allowing the user to load a separatedisk operating system to perform file management commands and load and save to disk. The most popular[citation needed] home computer, the Commodore 64, was a notable exception, as its DOS was on ROM in the disk drive hardware, and the drive was addressed identically to printers, modems, and other external devices.
More elaborate operating systems were not needed in part because most such machines were used for entertainment and education, and seldom used for more serious business or science purposes.
Another reason is that the hardware they used was (largely) fixed and a need for an operating system to abstract away differences was thus not needed. They shipped with minimal amounts of computer memory—4-8 kilobytes was standard on early home computers—as well as 8-bit processors without specialized support circuitry like a MMU or even a dedicated real-time clock. On this hardware, a complex operating system's overhead supporting multiple tasks and users would likely compromise the performance of the machine without really being needed.
Video games and even the available spreadsheet, database and word processors for home computers were mostly self-contained programs that took over the machine completely. Although integrated software existed for these computers, they usually lacked features compared to their standalone equivalents, largely due to memory limitations. Data exchange was mostly performed though standard formats like ASCII text or CSV, or through specialized file conversion programs.
Operating systems in video games and consoles
Since virtually all video game consoles and arcade cabinets designed and built after 1980 were true digital machines based on microprocessors (unlike the earlier Pong clones and derivatives), some of them carried a minimal form ofBIOS or built-in game, such as the ColecoVision, the Sega Master System and the SNK Neo Geo.
Modern-day game consoles and videogames, starting with the PC-Engine, all have a minimal BIOS that also provides some interactive utilities such asmemory card management, audio or video CD playback, copy protection and sometimes carry libraries for developers to use etc. Few of these cases, however, would qualify as a true operating system.
The most notable exceptions are probably the Dreamcast game console which includes a minimal BIOS, like the PlayStation, but can load the Windows CEoperating system from the game disk allowing easily porting of games from thePC world, and the Xbox game console, which is little more than a disguised Intel-based PC running a secret, modified version of Microsoft Windows in the background. Furthermore, there are Linux versions that will run on a Dreamcastand later game consoles as well.
Long before that, Sony had released a kind of development kit called the Net Yaroze for its first PlayStation platform, which provided a series of programming and developing tools to be used with a normal PC and a specially modified "Black PlayStation" that could be interfaced with a PC and download programs from it. These operations require in general a functional OS on both platforms involved.
In general, it can be said that videogame consoles and arcade coin operated machines used at most a built-in BIOS during the 1970s, 1980s and most of the 1990s, while from the PlayStation era and beyond they started getting more and more sophisticated, to the point of requiring a generic or custom-built OS for aiding in development and expandability.
Personal computer era
The development of microprocessors made inexpensive computing available for the small business and hobbyist, which in turn led to the widespread use of interchangeable hardware components using a common interconnection (such as the S-100, SS-50, Apple II, ISA, and PCI buses), and an increasing need for "standard" operating systems to control them. The most important of the early OSes on these machines was Digital Research's CP/M-80 for the 8080 / 8085 / Z-80 CPUs. It was based on several Digital Equipment Corporation operating systems, mostly for the PDP-11 architecture. Microsoft's first operating system,MDOS/MIDAS, was designed along many of the PDP-11 features, but for microprocessor based systems. MS-DOS, or PC DOS when supplied by IBM, was based originally on CP/M-80. Each of these machines had a small boot program in ROM which loaded the OS itself from disk. The BIOS on the IBM-PC class machines was an extension of this idea and has accreted more features and functions in the 20 years since the first IBM-PC was introduced in 1981.
The decreasing cost of display equipment and processors made it practical to provide graphical user interfaces for many operating systems, such as the generic X Window System that is provided with many Unix systems, or other graphical systems such as Microsoft Windows, the Radio Shack Color Computer's OS-9 Level II/MultiVue, Commodore's AmigaOS, Atari TOS, Apple'sMac OS, or even IBM's OS/2. The original GUI was developed on the Xerox Altocomputer system at Xerox Palo Alto Research Center in the early 1970s and commercialized by many vendors throughout the 1980s and 1990s.
Since the late 1990s, there have been three operating systems in widespread use on personal computers: Microsoft Windows, Apple Inc.'s OS X, and theopen source Linux. Since 2005 and Apple's transition to Intel processors, all have been developed mainly on the x86 platform, although OS X retainedPowerPC support until 2009 and Linux remains ported to a multitude of architectures including ones such as 68k, PA-RISC, and DEC Alpha, which have been long superseded and out of production, and SPARC and MIPS, which are used in servers or embedded systems but no longer for desktop computers. Other operating systems such as AmigaOS and OS/2 remain in use, if at all, mainly by retrocomputing enthusiasts or for specialized embedded applications.
Mobile operating systems
In the early 1990s, Psion released the Psion Series 3 PDA, a small mobile computing device. It supported user-written applications running on an operating system called EPOC. Later versions of EPOC became Symbian, an operating system used for mobile phones from Ericsson, Motorola, and Nokia. In 1996, Palm Computing released the Pilot 1000 and Pilot 5000, running Palm OS. Microsoft Windows CE was the base for PocketPC 2000, renamed Windows Mobile in 2003, which at its peak in 2007 was the most common operating system for smartphones in the U.S.
In 2007 Apple introduced the iPhone and its operating system, iOS, which, likeOS X, is based on the Unix-like Darwin. In addition to these underpinnings, it also introduces a powerful and innovative graphic user interface – later also used for the tablet computer iPad. A year later, Android was introduced, based on the Unix-like Linux, and its own graphic user interface, and Microsoft re-entered this market with Windows Phone in 2010, due to be replaced byWindows 10 Mobile in 2015.
In addition to these, a wide range of other mobile operating systems are contending in this area.
source wikipedia
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