Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uwm.edu!ogicse!plains!overby From: overby@plains.UUCP (Glen Overby) Newsgroups: comp.os.minix Subject: Re: A real operating system ? Summary: I prefer a virtual operating system. Keywords: future 1.5 Message-ID: <3696@plains.UUCP> Date: 2 Mar 90 23:29:29 GMT References: <1383@Terra.cc.brunel.ac.uk> <25eda193.62e3@polyslo.CalPoly.EDU> Reply-To: overby@plains.nodak.edu (Glen Overby) Organization: North Dakota State University, Fargo Lines: 42 In article <1383@Terra.cc.brunel.ac.uk> eesrajm@cc.brunel.ac.uk (Andrew J Michael) writes: >Several people have recently commented that MINIX is a teaching operating >system, not a real one. >So what makes a real O/S ? Is it the O/S itself, or the utilities which >come with it ? Both. The kernel alone isn't of much use; you need to surround it with good tools. Some people have faulted Minix for only using 64K segments. I think there are very good reasons for doing this on 8088s: there is much less of a chance of programs running over each other if they do not touch the segment registers. The compilers are easier to write, too. Minix on 80386s will run 32-bit segments, so you can have your GNUisms and other memory-hungry programs. I haven't seen a real Unix that allows huge model programs on an 8088 or 80286. The problems of device compatability we have encountered with Minix are no different than what any other multitasking operating system (i.e. one that does not rely soley on the ROM BIOS for it's I/O) has encountered. I think there are two things left to make Minix an extremely usable system: (1) the ability to swap, thus allowing iddle programs to be shoved out of memory, allowing larger programs to use available memory. (2) the bottleneck in the filesystem and, to a lesser extent, the memory manager will have to be dealt with. The problem right now is that one process can quite effectively take over the system by keeping the filesystem busy. We've already seen one attempted solution to this: a "multitasking" filesystem. It was a bit ugly. I think a nicer solution will be to implement threads (aka lightweight processes, and probably a few other synonyms). Then it will be possible to have multiple threads of execution servicing requests in all of the servers and devices. I doubt Minix will ever become a serious alternative for businesses, but it should make a good a personal (or "hacker", if you will) operating system. -- Glen Overby uunet!plains!overby (UUCP) overby@plains (Bitnet)