I'll try to find the project again and post a link.
I don't know all the details, but it was something about programming a
device to turn it off, and using processor to turn it on, thus allowing for
some higher speed or something.
It apparently only worked with a specific model paralell port and I asume
this was a speed issue.

    KreAture

----- Original Message -----
From: "M. Adam Davis" <adampic@UBASICS.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Wednesday, January 22, 2003 7:31 PM
Subject: Re: oscilloscope pulse display


> Kyrre Aalerud wrote:
>
> >Not true Bob.
> >
> >I have seen higher frequencies generated by paralell port.
> >Noone higher than 200 MHz though.  By bit-banging 8 bits paralell instead
of
> >doing a normal write you can get 4 mbyte transfer over a paralell link if
> >you're lucky...
> >
> >    KreAture
> >
> >
> Really?  I'd be interested in seeing how this is accomplished.  I
> suppose if you take a newer intel machine with a front side bus of
> 533MHz you could design the parallel port into the northbridge and
> /possibly/ change the state of the port 400MHz if you had all your code
> in the cache, ran off registers in the CPU, and didn't require any other
> system resources or listen to any interrupts.
>
> The front side bus is the speed at which the CPU communicates with
> everything on the systemboard.  Unless there's a trick that I don't
> understand, you cannot transfer more than 32 bits of data into or out of
> the processor more than X times a second, where X is the front side bus
> speed.
>
> A 4M Byte per second transfer from the parallel port only requires 4MHz
> speed, which is very achievable via the normal route
> (CPU-->Northbridge-->Southbridge-->PCI Bus-->Parallel port (with
> possibly an ISA bridge in there as well, though that could be a limiting
> factor))
>
> -Adam
>
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