For some reason, all copies of an early variant of RTLinux called “myrtlinux” by its Italian “author” have disappeared from the web, but thanks to some archives we can find some fragments from old days.  For example, within a year or two of this email, the story had changed rather  dramatically. To me, there were important lessons about the memories of academics who could get grants by not remembering and the principles of  “free software” advocates who could get  paid by being indignant in the right direction. (sorry if this is too cryptic, but I want to get some of this material back on line for a variety of reasons).

From:       mante () aero ! polimi ! it (Paolo Mantegazza)
Date:       1998-03-16 15:52:14
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Hello, fresh news on using the FPU within RTLinux.
I've been able to convince a collegue, performing active vibration control
of plates to decrease the transmitted noise, to use RTLinux with the FPU
support of my variant. (I was smart in having the other take the risk,
wasn't I?). Please note that is the same technique I posted some time ago
for an rt_prio_sched of the standard release.
They are sampling the response of three piezosensors, carry out some signal
conditioning and simple compensation and evaluate a direct proportional
feedback to actuate three piezoactuators. They use a 200 Mhz plain Pentium
and  conditioning and feedback are performed by using the FPU without any
problem, with X running and with the system lively, at 18 Khz. The signal
are checked on a scope.
For those interested the piezo sensors and actuators are three ceramic disks
bonded to the panel. The DA acquisition are carried out with a DAS1600 card
along with two DA conversions, the third DA output with some other card
whose brand I forgot.
This is a preliminary activity in view of the implementation of a neural
controller. The only way they found to crash the system was to unplug the
computer by stepping onto a flying socket.
After these simple tests their doubts on using RTLinux are fading away and
I am happy that they can trust me somewhat more now.
I have not checked the system personally yet, but this is just a
confirmation of my testings.
Having understood that "fixed FPU support" meant "sound and working" I'm
eagerly waiting for the new 2.2.xx related RTLinux release with a native
improved FPU support.
Ciao, Paolo.