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

Erie Patsellis erie at shelbyvilledesign.com
Fri Aug 22 17:38:50 CDT 2008

I can offer only this advice, for printers and the like, they work fine, 
for any applications that utilizes or needs coordinated movement or data 
pattern, it just won't happen consistently, if at all. As I mentioned 
earlier, I have some experience with using the parallel port for CNC 
applications, and believe it or not, you can get 6 axes of step and 
direction signals at a 450khz clock rate, coordinated. (Coordinated 
movements are a "gotta have" for these applications, plotting a circle 
with un-coordinated movements can result in some strange looking shapes, 
to say the least.)

The particular software package (Mach 3) that I use also allows numerous 
options for I/O, from a second parallel port for 16 bits of digital i/o, 
to a modbus board that allows quite a few more.

Richard wrote:
> In article <200808220430.AAA25423 at Sparkle.Rodents-Montreal.ORG>,
>     der Mouse <mouse at Rodents-Montreal.ORG>  writes:
>> I've moved small fractions of my applications into the kernel, inside
>> the lpt driver.  This was feasible because I was talking to, y'know, a
>> parallel port: write bits here and they show up on these wires, read
>> from there and you get the signals from those wires.  If I'd had
>> something like USB getting underfoot, this would probably have been
>> somewhere between annoying and impossible, instead of trivially easy.
> ...but meanwhile, this whole discussion is moot because you haven't
> actually tried it with USB, have you?  You qualify your statements as
> something akin to "I haven't tried it, but it probably won't work" but
> I don't see anything convincing me it won't work, just that you're too
> much of a stick in the mud on this issue to give it a try.

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