gheskett at wdtv.com
Fri Dec 18 16:37:33 EST 2015
On Friday 18 December 2015 14:23:01 Lucian wrote:
> I apologize for the scant previous message -- i really didn't think i
> would get any kind of response....
> My name is Lvcian. I work as an electronics technician for a
> geo/cosmo-chemistry research group at UCLA. There three big SIMS
> (secondary ion mass spectrometry) instruments in our facility in
> addition to various other diagnostic auxiliary scientific
> instruments--but the main instruments are all controlled by 68K-series
> motorola VME computers. I recently decided to teach myself as much
> about these computers as I can and have begun to build a 68008-based
> single board computer to play with real time operating
> systems.......this is how i came to find out about OS-9 and microware.
> I would like to play/learn these vintage UNIX-like computing
> environments .....but trying to do anything series aside from being
> better informed and do a better job at upkeeping and maybe int he
> future upgrade the instruments i maintain.
> what kind of work do you do ?
> Best Regards,
You had better have a pretty loose definition of "real-time", because
that 68008 isn't about to be a sub 10 microsecond response time
I run LinuxCNC on 3 CNC machines here, and the real-time portion of the
code is loaded when LCNC is run, with the linux kernel getting whatever
time the RTAI patches don't use. On certain motherboards, the latency
timings of a 25 microsecond loop can be as little as 2 microseconds of
jitter. That is as close as you can get to realtime when using software
to drive a batch of stepper motors.
Aftermarket I/O cards can reduce that to 15% of that or less, driving
steppers at 350 or more kilohertz.
Not at anything resembling full torque, thats one of the downsides to
steppers due to using a voltage less than required to get full current
thru the coils when the impedance becomes several times the ohmic as the
step pulses arrive faster and faster.
But that speed limit is several times as fast as the tool can be driven
to cut a path thru steel in most cases where spindle motor power and
available rpms, plus coolant flow, will allow without tool breakage.
That path, when measured, will, if the machine and software are properly
calibrated, be within a micron of a straight line over any arbitrary
distance and angle.
Check the kernel used in the hybrid-iso you can get just by downloading
it from linuxcnc.org.
As for work, I am a long retired television Chief Engineer, now doing
both metal and wood on machines I have rebuilt and converted to CNC.
Another member of this list is doing cnc work, on a small table topper he
built, and is using the coco as a controller. Perhaps he will stick up
Cheers, Gene Heskett
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Some mill pix are at:
Genes Web page <http://geneslinuxbox.net:6309/gene/GO704-pix>
More information about the Coco