> Sort of. It's perfectly possible to start Linux from DOS -- that's exactly > what LOADLIN does (load kernel image into memory, jump to the entry point -- > the 'kernel' entry point is usually the top of a decompression routine which > unpacks the kernel itself and jumps to the true entry point, which starts > the OS), and is also how NetWare works. NetWare is kinda unique in that it > doesn't overwrite DOS unless told to -- unless one issues the REMOVE DOS > command at the System Console, one can DOWN the server and EXIT back to DOS. > That's probably because NetWare 2 used to be able to run in either dedicated > or non-dedicated (the machine still works as a DOS machine) mode.
Yes. Thanks. A couple other people pointed out these programs to me yesterday. Obviously, they work beyond the scope of my current position on the learning curve. (no surprise, there<g>) I think I will continue on my current plodding course, learning how one operating system actually 'does its stuff' before I try tackling these more advanced topics, but at least I now know of their existence. I am still working on understanding the difference between the flat model and segmented model of addressing memory in the x86 processor. Heh. > The main problem with running multiple operating systems at the same time is > simply design -- an OS is designed, through necessity, with the assumption > that it will be the only OS in use and so has full control of the machine's > resources. To get to a point where two OSes can run on the same machine, a > virtualisation technique must be employed. IBM mainframes have been doing > this for decades, and on the PC we have VMware (an excellent piece of > software) and plex86 (LGPLed VMware-type project, has a lot of potential but > right now also needs a lot of work). DOSemu fits into that category too. > We also have emulators like bochs (LGPLed x86 emulator on lots of > platforms -- it runs on x8 Unix, Win32, Solaris on Sun hardware, etc.) and > Wine or WABI (Windows applications run under Unix with emulation of the > APIs), which are slower than virtualisation techniques but still very > useful. And then there are things like User-mode Linux, which will boot a > Linux kernel as a Linux application. I'm not sure how that works -- I think > it's VM-based. I did know about 'Wine', and emulators, but those, as I understand it, are not operating systems, but just programs that provide an interface layer between the non-OS programs, and the OS, to direct I/O and resource allocations properly. > For those of us with powerful enough machine, VMware is an ideal solution to > running multiple OSes -- I often have a NetWare server or two plus a couple > of Linux machines running while I'm working in Windows on this machine. It > does require quite a bit of grunt to make work though -- I've got dual > 800MHz processors in this box, and seriously fast RAM. My most powerful machine is no-where near powerful enough to do this; a single PIII processor, 128MB RAM. My older 386 and 486 boxes are amazingly slower and smaller, in every respect (except for the physical boxes themselves<g>) For what I am doing now, these are probably going to be more than sufficient for the next several years. Most of the programs I write now are student level, and not very resource hungry, and online activities seem to have hit a 56K ceiling for the time being, since modem communications are still the only connection available to the vast majority of users, and anything I post to my website is designed with those viewers in mind. Thanks for the info! This is one the most informative lists I subscribe to. -wittig http://www.robertwittig.com/ "Never hold a dustbuster and a cat at the same time." -Kyoyo, age 11 To unsubscribe from SURVPC send a message to [EMAIL PROTECTED] with unsubscribe SURVPC in the body of the message. Also, trim this footer from any quoted replies. More info can be found at; http://www.softcon.com/archives/SURVPC.html
