Re: emc on microway alpha pc?

["Matt Shaver" <mshaver-at-erols.com>]

> From: Jon Elson <jmelson-at-artsci.wustl.edu>
> >"Terry L. Ridder" wrote:
> > in talking with matt shaver concerning intel hardware
> > limiting the ability of emc to drive steppers currently
> > i was thinking of trying the alpha since the hardware
> > is a little different and should not be the limiting
> > factor. matt, sent me an excel spreadsheet which showed
> > the limits under intel hardware.
> 
> Hmmm, I'd like to see that.

Sure! It's at:

http://users.erols.com/mshaver/stepfreq.xls

As far as the ISA bus, parallel ports, and step pulse output goes, I don't
think that ISA port are too slow for step and direction output. The problem
with ISA was that the 8254 is on the ISA bus and reprogramming the interrupt
rate takes too long (like 10uS I think), so we couldn't schedule pulse
outputs by using the 8254 in one-shot mode. That forced us into periodic mode
and smack into the granularity problem. On the other hand, who knows what
cool timing hardware lurks inside Terry's Alpha? And for that matter, has
RTlinux been ported to that platform in a way that takes advantage of the
(possibly) better hardware?

Matt