Re: Is this true?

[pausch@saaf.se (Paul Schlyter)]

In article <1%EA9.22550$ME6.12791@rwcrnsc53>,
Richard Harvey <richattri@yahoo.com> wrote:
 
>> Maybe I am blind, but I know that when I use Windows XP I seem to have
>> an easier time using older Windows 98/95 software or even DOS software,
>> than if I were using Mac OSX and using ProDOS (Apple II software) or
>> Mac OS classic software.
> 
> So what. Win95 software is not even a decade old; that's no big deal. Try
> running some Windows 1.0 or 2.0 software under Win9x/NT/2K/XP and see how
> far you get -- not bloody likely you'll get more than a blue screen.
 
Win 1.0 (the OS) ought to run quite nicely within a DOS box of a
modern Windows version, since Win 1.0 ran in Real Mode.  And within
Win 1.0, Win 1 applications should be running --- however there were
very few such applications; you'll be lucky if you find any at all.
 
> And, the only reason DOS apps still work is that Intel is totally
> chained to an instruction set dating back to the 8086.  Fairly easy
> to remain compatible when you run on 70's technology.
 
There's more to DOS than just the CPU instruction set.  In particular
there's a specific hardware environment, and all of memory (within
the 1 MB which is addressable in Real Mode) is accessible to any DOS
program.  Modern Windows versions does a quite good job in emulating
this environment, but it's just because some effort was put into it.
 
The reason a similar effort wasn't put in emulating Windows 1 and 2
is that there were so little software for these Windows versions.
Windows didn't take off until verison 3.  But for plain MS-DOS there
were huge amounts of software, much of which still is accessible
throught the SimTel archives.
 
> Why aren't you asking why you are losing upwards of 50% or more in
> performance when Windows or your chip has to switch back into 16-bit
> compatibility mode to run some device driver or codec? That's the
> price you are paying for that wonderful DOS compatibility.
 
Losing only 50% in performance when emulating an older OS is quite
good actually; when emulating you can otherwise easily lose 90% or
more in performance.  Also on a 2.8 GHz Pentium, losing some 50-70%
in performance means you'll get some 1-1.4 GHz effective CPU speed
when running emulated MS-DOS on such a machine --- this is probably
much faster than the original hardware which ran these DOS programs,
at perhaps 0.005-0.020 GHz....
 
> I agree with another poster -- when/if you have the need to run ancient
> apps, keep a handy personal collection of the hardware you'll need.
 
....or a collection of emulators.  Old hardware occupies space, and
emulators on modern computers will be faster anyway than the original
hardware....
 
-- 
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