Re: 80286 protected mode

According to Anton Ertl <anton@mips.complang.tuwien.ac.at>:

Here's another speculation: The 286 protected mode was what they
already had in mind when they built the 8086, but there were not
enough transistors to do it in the 8086, so they did real mode, and in
the 80286 they finally got around to it.  And the idea was (like AFAIK
in the iAPX432) to have one segment per object and per procedure,
i.e., the large memory model.

If you look at the 8086 manuals, that's clearly what they had in mind.

What I don't get is that the 286's segment stuff was so slow.  Even
if you wanted to write code that put objects in segments, you really
couldn't.  You had to minimize the number of segment switches to get
decent performance.

Would it have been differently if the 8086/8088 had already had
protected mode?  I think that having one segment per object would have
been too inefficient, and also that 8192 segments is not enough for
that kind of usage, ...

That's all true, but I'd think the slowness of segment switches would
be even more of a problem.

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