On Wed, 24 Oct 2012 18:11:53 -0500, Char Jackson wrote:
> On Wed, 24 Oct 2012 17:04:30 +0000 (UTC), Stefan Patric
> <
n...@this.address.com> wrote:
>
>>On Tue, 23 Oct 2012 01:57:11 -0700, David Kaye wrote:
>>
>>> "Stefan Patric" <
n...@this.address.com> wrote
>>>
>>>> Of course, you could switch to Mac or Linux as more and more
>>>> dissatisfied Windows users (and businesses) have done and are doing.
>>>
>>> What good would THAT do? Mac keeps changing its operating system and
>>> making older software obsolete, requiring buying new updates.
>>> Windows, on the other hand, runs legacy software with ease! I have a
>>> music program called Band in A Box that was written for Windows 95 and
>>> works just fine on Vista and Windows 7, as well as XP. I have even
>>> older Usenet news reader software called News eXpress which was
>>> written for Windows 3.1, and even this software runs fine on later
>>> Windows versions, even though it's about 20 years old!
>>>
>>> Just try THAT with a Macintosh.
>>
>>You do it on a Mac the same way it's done on Windows: virtual machines
>>and emulation. (You can even run Windows on a Mac this way. Linux,
>>too.)
>
> I think the difference is that the need is relatively rare in the
> Windows world and much more common in the Mac world.
Actually, it's the other way around: There's more emulating needed with
Windows to support all the Windows (and DOS) legacy apps than with the
Mac. The "legacy" with the Mac is those apps before OSX, where full
virtual machine emulation is required on an OSX machine to run them. OSX
is OSX, more or less. If your app ran on 10.X, it will run on 10.Y. Of
course, there are exceptions. Perfection is impossible, but almost
perfect is attainable.
>>What do you think XP Mode on Windows 7 is? Running 16-bit legacy apps
>>natively ceased with Windows 2000, IIRC. Since then backward
>>compatibility is done through emulation even if it's not apparent.
>
> In the Windows world, a 32-bit OS can typically run 32- and 16-bit
> software natively, while a 64-bit OS can typically run 64- and 32-bit
> software natively. There is a 32-bit version of Windows 7, if people
> want it, so that's one possible path still available to running 16-bit
> software natively. Naturally, the 32-bit versions of Vista and XP could
> do it, as well.
All very incorrect. 16-bit, 32-bit, and 64-bit code are totally
incompatible with one another. One won't run on the other without help,
that is, some type of emulation. This can be full emulation--target OS
running in a virtual machine--like XP Mode on W7, or a System Call
Translator and OS spoofer like Compatibility Mode where the target OS is
not needed.
Windows lost the ability to run 16-bit natively with Windows 2000 which
was totally 32-bit with no DOS elements at all. Only Windows 9X and ME
with their hybrid 16/32-bit kernels could do it. Since that time, legacy
compatibility can only be achieved through various types of emulation
which for the most part is totally transparent to the user. The
emulation is part of the OS, and runs automatically when needed. The
emulators go by various names: NTVDM (NT Virtual DOS Machine),
Compatibility Mode, XP Mode, WOW64 (Windows 32-bit On Windows 64-bit),
etc.
Now, 32-bit on 64-bit is a special case. Both modern (the last 7 years
or so) AMD and Intel 64-bit CPUs have a built-in 32-bit execution mode.
That's how you can install and run a 32-bit OS on a 64-bit CPU, and have
it work. (Remember, 32-bit and 64-bit are totally incompatible.) The
added advantage is that if you're running a 64-bit OS, you can run a 32-
bit app without any software emulation. The CPU itself takes care of
it. So, virtually native execution as far as the OS is concerned. The
only thing required is the 32-bit OS libraries must be installed. (The
64-bit libraries are incompatible with 32-bit.) This is the way OSX and
Linux work. I've never checked how Windows does it, but I imagine it's
similar, but with software tweeks provided by WOW64.
Some links below, FYI:
http://www.enterprisenetworkingplanet.com/netos/article.php/600311/
Running-16Bit-Applications-as-a-Separate-Process.htm
http://www.techrepublic.com/article/get-it-done-make-legacy-applications-
feel-at-home-in-windows-xp/1055657
http://msdn.microsoft.com/en-us/library/aa384249(v=VS.85).aspx
http://www.techsupportalert.com/content/how-windows7-vista64-
support-32bit-applications.htm
Stef