The MacIntosh not a true multitasking system in the sense that if one program

The macintosh not a true multitasking system in the

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this relies on each program obeying specific rules in order to achieve the illusion. The MacIntosh not a true multitasking system in the sense that, if one program crashes, the whole system crashes. Windows is purported to be preemptive multitasking but most program crashes also crash the entire system. This might be due to the lack of proper memory protection. The claim is somewhat confusing. AmigaDOS is an operating system for the Commodore Amiga computer. It is based on the UNIX model and is a fully multi-tasking, single-user system. Several programs may be actively running at any time. The operating system includes a window environment which means that each independent program has a `screen' of its own and does not therefore have to compete for the screen with other programs. This has been a major limitation on multi-tasking operating systems in the past. MTS (Michigan timesharing system) was the first time-sharing multi-user system 1.2 . It supports only simple single-screen terminal based input/output and has no hierarchical file system. Unix is arguably the most important operating system today, and one which we shall frequently refer to below. It comes in many forms, developed by different manufacturers. Originally designed at AT&T, UNIX split into two camps early on: BSD (Berkeley software distribution) and system 5 (AT&T license). The BSD version was developed as a research project at the university of Berkeley, California. Many of the networking and user-friendly features originate from these modifications. With time these two versions have been merged back together and most systems are now a mixture of both worlds. Historically BSD Unix has been most prevalent in universities, while system 5 has been dominant in business environments. The trend during the last three years by Sun
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Microsystems and Hewlett-Packard amongst others has been to move towards system 5, keeping only the most important features of the BSD system. A standardization committee for Unix called POSIX, formed by the major vendors, attempts to bring compatibility to the Unix world. Here are some common versions of UNIX. Unix Manufacturer Mainly BSD / Sys 5 BSD Berkeley BSD SunOS (solaris 1) Sun Microsystems BSD/sys 5 Solaris 2 Sun Microsystems Sys 5 Ultrix DEC/Compaq BSD OSF 1/Digital Unix DEC/Compaq BSD/sys 5 HPUX Hewlett-Packard Sys 5 AIX IBM Sys 5 / BSD IRIX Silicon Graphics Sys 5 GNU/Linux Public Domain Posix (Sys V/BSD) SCO unix Novell Sys 5 Note that the original BSD source code is now in the public domain. Unix is generally regarded as the most portable and powerful operating system available today by impartial judges, but NT is improving quickly. Unix runs on everything from laptop computers to CRAY mainframes. It is particularly good at managing large database applications and can run on systems with hundreds of processors. Most Unix types support symmetric multithreaded processing and all support simultaneous logins by multiple users.
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