[OpenBIOS] OpenBIOS: reality check

[Pascal Dornier]

>I believe the main problem of today's BIOSes is that they're designed to
run in
>real mode. A protected mode OS will either have to switch to and from real
and
>protected mode to perform I/O (which isn't very neat, and incurs quite a
lot
>of execution overhead) or ignore the BIOS entirely and provide its own I/O
>routines (which is a waste of coding effort). It'll be good if there's a
BIOS
>that can provide some sort of protected mode framework (possibly amounting
to
>a microkernel?) within which an OS can access BIOS services in true
protected
>mode. (Proprietary ROM BIOS extension cards will probably have to be
modified
>to fit into this scheme, but that's another story...)


That's been done in 1987, the so called ABIOS (advanced BIOS) in IBM's
PS/2 systems. It was intended to be for OS/2. I don't know whether it
got used at all, but the idea died together with the Microchannel
architecture. Nobody missed it ever since...

Today's protected mode OSs use their own drivers to avoid switching
modes. And switching modes on 386 and later CPUs is much faster than
it was on the "brain-damaged" 286.

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Pascal Dornier   pdornier at pcengines.com     http://www.pcengines.com
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