22 Jul
2012
22 Jul
'12
11:24 a.m.
Rob Doyle
<radioengr at gmail.com> writes:
> It was never intended to do DOS. It was an embedded controller.
> Most of the peripherals were not PC compliant and they certainly
> weren't mapped at the right IO addresses.
>
> In fact, Intel made it a point to tweak the embedded controllers so
> that they *could not* run DOS and they could sell them at embedded
> processor prices. Witness the 80376 and 80386EX.
The 80186 was released in 1982 and had been in beta quite a bit
longer (I used pre-release steppings and still remember some of the
nastier bugs). Intel had no way to know that the 5150 and its
descendents would be popular at all; in fact, while the 186 was in
development, I don't think that the subject of DOS had even been
settled.
The primary issue is that the integrated peripherals, are substantial
improvements over the old 8085-era legacy chips used by IBM. For
example, the integrated DMA uses the full 20 bit address space, not
some crufty 64K piece of it.
It should also be noted that the 80186 was the first ti improve on
the instruction set of 8086, adding the non-privileged instructions
of the 80286.
It's entirely possible to discard the internal peripherals and employ
the old legacy garbage, but then, what would be the point of using an
80186? But there were several systems that used special versions of
DOS and ran very nicely on the 80186.