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    SubjectRe: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops
    On Sat 2007-12-08 14:25:02, David P. Reed wrote:
    > Alan Cox wrote:
    > >
    > >0x80 should be fine for anything PC compatible anyway,
    > >its specifically
    > >reserved as a debug port and supported for *exactly*
    > >that purpose by
    > >many chipsets.
    > >
    > >
    > Disagree. The definitions of PC compatible are quite
    > problematic. I have the advantage over some of you
    > young guys, in that I actually wrote code on one of the
    > first 5 breadboard IBM PCs on the planet at Software
    > Arts, Inc. and I was directly involved in hardware spec
    > projects with the original IBM and Compaq engineers. No
    > one actually defined the port numbered 80h as a
    > "standard" for anything. You won't find it documented
    > in any early manual for an IBM machine.
    > The ISA bus supported unterminated transactions safely.
    > That allowed some clever folks to design BIOS diagnostic
    > tools that optionally plugged into the bus.
    > In any case, my machine does not have an ISA bus. Why
    > should it? It's a laptop!

    There are mini-pci based cards with port 0x80 displays for notebooks.

    (cesky, pictures)

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      Last update: 2007-12-09 19:09    [W:0.030 / U:4.764 seconds]
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