Unix and real time control

[DMS%MIT-OZ at MIT-MC.ARPA]

From:  David Siegel <DMS%MIT-OZ at MIT-MC.ARPA>

Hi,

We are planning to use a Vax 11/750 in a real time control
application. Rumor has it that Unix is not very good for real time
control. This leads to two questions:

1) Is the rumor true, and if so what are the problems?

2) Are there any verions of Unix floating around that are especially
   designed for real time applications.

Note: 
  We are using the vax to servo actuators for a robot at rates that
  vary from 40 to 300 cycles per second. We will be needing interrupt
  response from the vax, although it is not clear how fast a response
  rate we need.

Should we stick with VMS, or will some Unix handle our needs
adequately?

Thanks for any help you can give.

-Dave & Sundar