Re: Is this true?

["Bryan Villados" <news002@macgeek.org>]

First of all, unlike what a lot of people want to believe, even the Pentium
IV chip of today is still working with quite a bit of the very old
technology the Intel 8086/8088 had. In short, that's the reason why you
could, in theory, boot a Pentium IV with CP/M-86. The latest CPU I've tried
this test with was a Pentium, and it booted fine.

I don't believe the Pentium series ever went totally RISC like the PowerPC
chip. From my understanding, even today's Windows software is still being
written using a form of CISC instructions rathar than RISC. Intel and
Microsoft believe more in downward compatibility through hardware than
Apple. And, there are both upsides and downsides to that philosphy. Though
it's a lot harder to keep up with Apple's changes via software, the
progression of PC technologies because of the heavy legacy hardware that lag
with it is limited. However, within the last couple of years, that too is
changing (USB, FireWire, etc.)

On the Macintosh side, the PowerPC chip that run all the Power Macintosh
systems is nowhere an upgraded version of the Motorola 68000. The PPC, via
software emulation, has the ability to emulate 68000 instructions by turning
the RISC instructions into 68000 instructions. Also, much of the Macintosh
technology is based around the ROM, while the old PCs was based mostly on
the ROM-BIOS. Even when the Macintosh 128 came out in 1984, most of its
operation was running off of ROM, and less off of RAM. When Microsoft
Windows 1.0 came out later on, most of it ran off of RAM, and very little
off of the ROM-BIOS.

With that... At each advancement of the Macintosh, the routines in ROM and
in the operating system are refined with the times. When Mac OS 9.0 was
released awhile ago, a very large percentage of the library routines were
either re-written, or thrown out completely (this process is called
"carbonization", and the refined library is called "carbon"). That is why
compatibility with legacy software is less and less with each major release
of Mac OS software. If you think about it, Microsoft Windows is the same
way. With Windows XP, the 16-bit emulation that allows you to run Windows
3.x code is a lot lot less than when Windows 2000 was released, so you could
say that Microsoft is using the same logic as Apple when it comes to
cleaning up and optimizing their OS.

Looking at the Apple II series, you cannot draw a 100-percent conclusion
that all legacy Apple II software will run on the Apple IIgs, Apple's latest
Apple II computer. Even though the 65816 is supposedly downward compatible
to the 6502, from my understanding it is not 100-percent. Also, the hardware
architecture of the Apple IIgs is also not 100-percent downward compatible
with the earlier models as well. With that, even in the Apple II realm you
cannot guarantee 100-percent legacy compatibility on its latest model.

With all that behind, this is why I always encourage people to keep at least
one model of each generation. In my computer collection, I have an Apple
II+, IIe, IIgs, Mac Plus, Mac Color Classic, Power Mac 8600, and Powerbook
G3 Pismo running Mac OS X 10.2.2. With this kind of a set-up, I have
absolutely no problem running anything Apple that's thrown at me.

So again, the argument about Windows being compatible with legacy software
is by no means very accurate.

--- Bryan


"JWolf6589" <jwolf6589@aol.comnospam> wrote in message
20021113193218.21158.00000705@mb-cu.aol.com">news:20021113193218.21158.00000705@mb-cu.aol.com...
> I read this quote: "All PC-compatible computers (even a 1Ghz PIII) are
equipped
> with hardware to provide this backward compatibility and are therefore
able to
> execute the large no. of applications which have been developed for
> PC-compatible computers in the last 20 years."
>
> If PC's are designed so smart, howcome the MacOS or should I say OSX is
not
> designed to be 100% backward compatible with all software developed for
any
> Apple computer ?  I mean all my Apple II software will not work on a OSX
OS
> without a emulator, and some of my MacOS classic software will not run
under
> OSX.  It is true OSX does offer a classic compatibility mode, but using
this is
> KINDA like using a emulator.
> 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.
>
> Also on the PC I am able to partition a hard drive to use any Windows or
DOS
> OS, but on the Mac this is simply not true.  Its a pain as I have a few
usefull
> programs that will not work in a non OS 7.x environent.
> Hence the Macs shipping in 2003 will not even be able to boot Mac OS 9.x!
>
>
> John
>
>
>
> -----------------------
> John 3:16
> *Remove nospam to reply.