[rescue] Parallel ports [was Re: Slightly OT: ?Bad Cap Saga]

der Mouse mouse at Rodents-Montreal.ORG
Fri Aug 22 10:20:25 CDT 2008

>> Right.  At a severe (crippling, I suspect - hm, I should measure
>> this) speed cost: at least two syscalls - user/kernel crossings -
>> per byte, instead of one for the whole string.
> Why can't you use an existing "printer interface"?  Or, open /dev/lpt
> and write()-ing 500 bytes at a time?  One trap per call.

Because that's output-only, not "the output one byte, input one byte,
repeat" paradigm I'm actually using.

> The challenge I am issuing is to come up with something more general
> purpose (on the "application hardware" side) than a "parallel port"
> and more *portable* and future-safe on the "host" (PC) side.

As for the latter, there is no such thing.  Whatever hardware I pick is
vulnerable to being abandoned by computer makers much the way parallel
ports are being.

As for the former, that's Hard; how can you get more general purpose
than a bunch of undedicated signal wires?  A lot of applications need
something layered atop it, but that's true of USB (which is neither
universal nor a bus, but that's another rant), of Ethernet, of serial
lines, of everything that's been proposed.

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