OSDev.org

There are several dead, but great Operating System at one time.

What is your favourite "dead Operating System"?

Is it OS/2, BeOS, AmigaOS, DOS, OS/400, Mainframe OS or others?

Pitiful, I know, but it has to be MS-DOS 5 & 6

I used to enjoy having to play around with home-made boot floppies trying to tweak config.sys and autoexec.bat to attempt to get enough base RAM to play games such as Privateer II: The Darkening! Of course, with the later versions of DOS came memmaker to attempt to do that for you - it normally failed miserably.

I also remember on an old Apricot computer, you had to run the utility 'Parker' to park the drive heads before you could safely turn off the power. Ah - those were the days

Cheers,
Adam

Yeah I'm going to have to say dos too. I am not really old enough to remember any other operating systems so thats my only option. I still remember trying to program in QBasic.

Dos is not dead, there millions of users worldwide and lots of business software runs on it.
See FreeDos, also you can order a New DELL PC with freedos on it.

v2os 0.64 (floppy version), NOTE: 0.70 is fake
http://v2os.v2.nl/

OS/2 is not technically "dead" because IBM gave Serenity Systems the rights to continue the product line as eComStation. It's a fast and stable os with a simple, but pleasing gui. Unlike Windows NT and Mac OS X it doubles well as both an end user os and a server os.

binutils wrote:v2os 0.64 (floppy version), NOTE: 0.70 is fake
http://v2os.v2.nl/

DexOS, started as the rebirth of v2_os 0.64, but the mods wanted to stay with 0.70, so a group of us split from V2_os and did a totel rewrite, we based it on the design of the old v2_os 0.64 but not a single line of code was used from v2_os.
So you see the spirt of V2_os lives on in DexOS.

You can read the ups and downs of how DexOS started on the v2_os forum, it was code named v3os and i was called ASHLEY4.
http://v2os.v2.nl/phpbb/viewtopic.php?t ... sc&start=0

The native OS that ran on the Commodore 64/128. IIRC the entire OS was one large basic interpreter, and to load a program you would enter the basic commands for LOAD and then RUN.

If DOS used a flat memory model and all programs were loaded at the same address, how did DOS handle things such as opening command.com from within command.com? If they were loaded at the same address, would not the new command.com overwrite the original command.com? And how did DOS programs copy a new program to memory to execute them without overwriting it's own program?

DOS along with Windows 95, that has been my first combination of PC It had the best kickass games for a 486 (sorry, in 1999 ) - doom I and II, Duke Nukem 3D, Lotus III [port from Amiga], Lamborghini: American Challenge,... etc etc. I then (i was 6 years old), had absolutely no knowledge in PCs, and i was even worried to browse on C:\GAMES using Windows's Explorer. I started the games only by the "magical Start button" in W95 and ultimately, I started the PC only for games in that era. Eventually, in 7, my Win95 had corrupted by my fault: I pressed F8 during it's start and I selected "Earlier version of MS-DOS" in the boot menu. I didnt knew how to repair it, and Windows wasn't bootable now. Something about VFAT and BSOD I think... - I had to reinstall Win95, by myself, in my 7 !!! Thank god it was successful. But if Win95 would be in English version, I would fail. And thank God I had the C:\WIN95 directory on my former hard disk, it was the installation directory. Why? No one from my friends had computers, Win95 CD-ROM/floppys or any knowledge in repairing computers.

Regards
inflater

MessiahAndrw wrote:The native OS that ran on the Commodore 64/128. IIRC the entire OS was one large basic interpreter, and to load a program you would enter the basic commands for LOAD and then RUN.

no, that is the shell (and, iirc, it was licensed from microsoft btw)
the OS, ran under that (and was probably written in-house by CBM), most people were largely unaware of the existence of the kernel (which interfaced with apps through a jump-table)

If DOS used a flat memory model and all programs were loaded at the same address, how did DOS handle things such as opening command.com from within command.com? If they were loaded at the same address, would not the new command.com overwrite the original command.com? And how did DOS programs copy a new program to memory to execute them without overwriting it's own program?

that isnt true -- DOS didnt use a 'flat model', in fact, 'com' style applications are forbidden (though not enforced) to use more than 64k memory, and may be loaded anywhere in physical memory (the '.com' specification was 'borrowed' from the CP/M OS, which only supported 64k memory)
DOS itself, could load both native ("MZ") and CP/M-compatibility (".com") style programs anywhere in memory, and had (somewhat primitive) multi-tasking capabilities, and could allow many programs to run at once (however, it lacked the ability to protect applications from each other) and even supported features which allowed it to 'page out' portions of memory (though not to disk -- only to XMS or EMS memory -- though it was heavily dependent on application support for these features, which limited its usefulness)

as for loading "command.com"? its the shell -- just another CP/M application as far as DOS is conserned, and you can load many of those, as long as it doesnt run out of memory


as for overwriting itself, the DOS kernel is located high in memory (sometimes in the space above 1MB, or between add-in cards in the ROM area), the DOS shell, could be overwritten -- if the application asked for more ram than was availible, it would sacrifice parts of itself (the shell being the first to go) reloading these portions from disk when that application terminated)

JAAman wrote:the DOS kernel is located high in memory

In fact, I seem to remember the config.sys line DOS=HIGH in order to force that situation [showing signs of age!]

cheers,
Adam

Ah! memories! my favourite is the OS running on the Sinclair Spectrum.

Those were the days - writing programs in BASIC - everything was simplified because you didn't type "RUN", "FOR", "IF", etc, they were on the keys as shift-ctrl combinations. Makes parsing easier i suppose.

Having since written several embedded systems on a Z80 chip which the spectrum was based on, i have a new respect for the people who managed to write games on the 4MHz chip...