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SubjectRe: A/D converter
On Wed, 21 Apr 1999, David Woodhouse wrote:

>
> root@chaos.analogic.com said:
> > I hook a function generator to the printer port. The ioctl input to
> > the device atomically reads the longword and resets it to zero. The a
> > user-mode task reads this at 1-second intervals.
>
>
> Have you tried this with your function generator connected directly to the ISA
> IRQ line?
>
> It's possible that the printer port hardware has a filtering effect - you might
> well find that it's debounced.
>

It's not. Further, the exact same hardware runs about 10 times faster with
an ISR in DOS-real mode showing that the port itself is not the dominant
pole in the ISR bandwidth. Further, this was not a complaint, only a
_measured_ observation made independently by myself and an associate.

We needed to verify, by tests and measurements, what the interrupt
response time is, in preparation for an upcomming design review where we
put our jobs on the line as advocates of Linux instead of the Customer
required Windows-NT for a new project.

So I present my results and get hate mail from the world. This is
Bullshit.

Cheers,
Dick Johnson
***** FILE SYSTEM WAS MODIFIED *****
Penguin : Linux version 2.2.6 on an i686 machine (400.59 BogoMips).
Warning : It's hard to remain at the trailing edge of technology.


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