3 Aug
2008
3 Aug
'08
9:19 p.m.
On 3 Aug 2008 at 23:28, Sridhar Ayengar wrote:
I do design for a living, and, although your point
regarding being
unable to predict the future with perfect accuracy rings true, I would
argue that prototypes really help with getting the really big screw-ups
out of your designs.
I consider neither the reset vector nor the segmentation feature of
the 80x86 to be a design screw-up, but rather a design decision.
Regardless of the technical quibbling, it works.
Real screw-ups are the "you can't get there from here" sort--where
there are no good work-arounds and the problem prevents customers
from getting useful work done. Sometimes, this stems
from a
misunderstanding of the customer's needs.
For example, on the 80286, I can imagine an engineer saying to
himself "Once you've entered protected mode, why would you *want* to
go back to real mode?" Hence, the really weird kludge using the
keyboard controller to reset the CPU into real mode on the PC AT.
Without the then-undocumented LOADALL instruction, protected-mode
Windows may have been delayed until the 80386. Quel horreur!
Cheers,
Chuck