Re: IO delay, port 0x80, and BIOS POST codes

[Linus Torvalds]

On Thu, 14 Mar 2002, Richard B. Johnson wrote:
> 
> Well I can see why he's an EX-Phoenix BIOS developer. A port at 0xed
> does not exist on any standard or known non-standard Intel/PC/AT 
> compatible.

Note that "doesn't exist" is actually a _bonus_. It means that no 
controller will answer to it, which causes the IO to time out, which on a 
regular ISA bus will also take the same 1us. Which is what we want.

Real ports with real controllers can be faster - they could, for example,
be fast motherboard PCI ports and be positively decoded and be faster than
1us.

		Linus