Re: Byte ordering

David Brown <david.brown@hesbynett.no> writes:

On 04/10/2024 19:30, Anton Ertl wrote:

David Brown <david.brown@hesbynett.no> writes:

On 04/10/2024 00:17, Lawrence D'Oliveiro wrote:

Compare this with the pain the x86 world went through, over a much longer
time, to move to 32-bit.

>
The x86 started from 8-bit roots, and increased width over time, which
is a very different path.

 
Still, the question is why they did the 286 (released 1982) with its
protected mode instead of adding IA-32 to the architecture, maybe at
the start with a 386SX-like package and with real-mode only, or with
the MMU in a separate chip (like the 68020/68551).
 

>
I can only guess the obvious - it is what some big customer(s) were
asking for.  Maybe Intel didn't see the need for 32-bit computing in the
markets they were targeting, or at least didn't see it as worth the cost.

Anyone could see the problems that the PDP-11 had with its 16-bit
limitation.  Intel saw it in the iAPX 432 starting in 1975.  It is
obvious that, as soon as memory grows beyond 64KB (and already the
8086 catered for that), the protected mode of the 80286 would be more
of a hindrance than even the real mode of the 8086.  I find it hard to
believe that many customers would ask Intel for something the 80286
protected mode with segments limited to 64KB, and even if, that Intel
would listen to them.  This looks much more like an idee fixe to me
that one or more of the 286 project leaders had, and all customer
input was made to fit into this idea, or was ignored.

Concerning the cost, ther 80286 has 134,000 transistors, compared to
supposedly 68,000 for the 68000, and the 190,000 of the 68020.  I am
sure that Intel could have managed a 32-bit 8086 (maybe even with the
nice addressing modes that the 386 has in 32-bit mode) with those
134,000 transistors if Motorola could build the 68000 with half of
that.

It is fair enough to target the existing market, but they were also slow
(IMHO) to take advantage of new opportunities in hardware, re-enforcing
the situation.

They introduced Windows/386 in 1987.

I think MS and their monopoly on markets caused a
stagnation - lack of real competition meant lack of progress.

Monopoly?  These were the times with lots of competition from
different hardware and software manufacturers.  Apple with the Apple
II, Lisa and MacIntosh, Atari with their 8-bit line and ther Atari ST
line, Commodore with their 8-bit line and their Amiga line, and, on
the software side, Digital Research with CP/M(-86/68K) and GEM, and
various Unix offerings, including Xenix.  Were they all no real
competition?  Not in my book.  It's just that Microsoft eventually
won, maybe accidentially (as it happens in a winner-takes-all market).

IBM were famous for poor (and perhaps cowardly) decisions at the time,
and MS happily screwed them over again and again in regards to OS/2.

Another interpretation is that MS went faithfully into OS/2, assigning
not just their Xenix team to it (although according to Wikipedia the
Xenix abandonment by MS was due to AT&T entering the Unix market) and
reportedly also assigned the best MS-DOS developers to OS/2.  They
tried to stick to OS/2 for several years, but eventually were fed up
with all the bad decisions coming from IBM, and bowed out.

- anton
--
'Anyone trying for "industrial quality" ISA should avoid undefined behavior.'
  Mitch Alsup, <c17fcd89-f024-40e7-a594-88a85ac10d20o@googlegroups.com>