Re: [Gnu-arch-users] tla1.2 on cygwin

[Evan Powers]

On Tuesday 02 March 2004 11:48 pm, Adrian Irving-Beer wrote:
> On Tue, Mar 02, 2004 at 08:38:47AM -0800, Tom Lord wrote:
> > Yes, I know (although, don't they still contain some compatability
> > code or is that gone by now?).

To answer Tom's question, I think it's still around, though greatly reduced. 
You may still be able to run a DOS application which does nothing but call 
libc (well, msvcrt or whatever) functions, but versions circa Windows 9x 
tried to maintain more extensive compatibility, such as with DOS device 
drivers, graphical programs, and (I think) even TSRs. They don't bother with 
that anymore.

> Well, NT is/was an OS/2 kernel with a Windows GUI.  Win95/98/ME were a
> DOS kernel with a Windows GUI.

Are you sure about that? OS/2 is the name of IBM's operating system product 
which they designed, if I remember the story correctly, to KILL OFF Microsoft 
(among other things). NT, on the other hand, is an acronym for New 
Technology, whatever that means -- but I sincerely doubt it means IBM's OS/2.

I don't think they are the same thing.

That NT and Windows 9x/ME are based on different kernel codebases is certainly 
true, however.

> I believe the core of the OS/2 kernel was 'personalities' -- one
> personality when talking to DOS programs, one when talking to another
> class of programs, etc.

I know that the NT kernel does indeed have these "personalities", though not 
one for DOS as far as I know. The two traditionally mentioned ones are the 
(long since bit-rotten) POSIX personality and the Win32 personality we would 
normally think of. That's right, NT could, in theory, run POSIX programs 
natively, but I hear that it never quite worked correctly (bugs).

The really bizarre thing, IMHO, about NT kernel personalities is that they are 
completely disjoint. A process running inside the POSIX subsystem cannot call 
Win32 API functions, or indeed even be aware of running Win32 processes, and 
vice versa.

> Hence, NT actually had fairly good compatibility with DOS programs
> because it was like an early, more tightly-integrated VMware.

I don't think this is true. In fact, I believe the opposite: NT 3.x had 
absolutely no support for DOS programs. I think they shoehorned some 
compatibility into Windows 2000 to help convince people to upgrade, and I 
think I remember reading that XP has even better compatibility. Perhaps it 
was only that XP has better compability with Windows 95 than 2000 did, not 
DOS....

Evan