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SubjectRe: IO delay, port 0x80, and BIOS POST codes
Followup to:  <>
By author: "Richard B. Johnson" <>
In newsgroup:
> Well no, IO doesn't "time-out". The PC/AT/ISA bus is asychronous, it's
> not clocked. If there's no hardware activity as a result of the write
> to nowhere, it's just a no-op. The CPU isn't slowed down at all. It's
> just some bits that got flung out on the bus with no feed-back at all.

An OUT on the x86 architecture is synchronous... the CPU will not
proceed until the OUT is present on the bus. This is a requirement of
the SMM architecture, actually.

<> at work, <> in private!
"Unix gives you enough rope to shoot yourself in the foot." <>
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