🚀 go-pugleaf

in article <8904241544.AA21773@ucbvax.Berkeley.EDU>, 01659@AECLCR.BITNET (Greg Csullog) says:

> Someone please correct me if I am wrong, but my understanding of the 8088,
> 80286 and 80386 family is that the junior member (the 8088) requires memory
> segmentation to work (i.e. 10 banks of 64K). 

8088 segmentation is a little more sophisticated/complicated than simple
banking.  It manages 4 separate 64K chunks, along the Pascal programming
model.  Any code or data longer than 64K hits serious performance barriers.

The '286 and '386, when running MS-DOS, kick into a mode that completely 
emulates the 8088/8086 at the hardware level.  None of the new mode features
or instuctions are available.

> Even if you have an 80286 or an 80386, most codes out there are compiled to 
> run on the 8088 and still use the memory segmentation protocols. Therefore, 
> even if you have an 80286 or an 80386, with these segmented codes, you 
> cannot use the true power of the processors - all you can take advantage of 
> is the faster clock times.

Actually, the '286 native suffers from the same problems.  It's segmentation
scheme can address 16megs of RAM vs. the 1 meg of an 8088/8086, but it's
still limited by 64k segments.  

> Seems to me, if you use segmented codes on a 80286 machine, you're bound to 
> have a lower performance standard than a Mac or an ST with a 68000 and their
> codes which are not segmented. Is this right?

Very often right.  Depends on what you're doing.  The segment limitations of
a '286 in native or protected mode don't really get in the way until you 
start running larger programs.  So small programs can run the same, or
faster, than on 68000 machines (though a smart 68000 compiler can use base
register addressing to achieve the same economy for small programs).  The
success of the '286 is largely the momentum of the PC industry, not anything
especially good about the processor itself ("brain damaged" was how Steve
Ballmer of Microsoft once described the '286).

The '386 adds full 32 bit addressing and a paging MMU to it's native mode.
It's not quite an '030, but it's certainly a step in the right direction.

> The latest issue of Current Notes has an article by G. Louie of Sphere Inc.
> berating the ST market for piracy. 

While piracy in any market is a bad thing for that market, you really have
to think of it differently for the ST or Amiga markets vs. the PC or even
the C64 market.  I have no doubts that business folks buy PCs and swipe
programs from work for home, and that kids buy C64s to copy the software
their friends have.  Thing is, there are some 7-9 million C64s and around
12-15 million PCs out there.  That kind of piracy, even if on the same
percentage basis as in the ST market, can't kill either machine.  But it
can kill the ST market if developers get frightened away.  

You hear people yell and scream about how loyal they are to a machine like
the ST, for instance.  Next thing you know, they're telling you about this
great stash of pirate software they've got on their BBS.  They'll undoubtedly
come up with some rationalization for it, but regardless, they're doing harm.
And in a small market, that harm can be enough to kill.  I know, my job
ultimately depends on the success of the Amiga, and that winds up depending
on folks to buy software for the machine, plain and simple.


-- 
Dave Haynie  "The 32 Bit Guy"     Commodore-Amiga  "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: D-DAVE H     BIX: hazy
              Amiga -- It's not just a job, it's an obsession