Real-Time UNIX Question

[Charles Noren]

I am on a small project with a limited budget ($50-60K for hardware)
that needs to read modest amounts of information off of 16 asynch serial
ports from various devices (handle bursts of 10 60-byte messages/minute
for 10 minutes -- only a guess).  Are there any UNIX machines that anyone
would recommend?  We have been considering SUN 3,  MASSCOMP (Concurrent
Computer Corp), MicroVAX with ULTRIX.  Also, we have noticed that
MASSCOMP has some real-time extensions to its UNIX (e.g., VMS type AST's).
Has anyone had any experience with them?  Do they conform to emerging POSIX
standards?  I'm familiar with BSD.  Does System V offer some things I
need to consider?
Thanks in advance for your help.
-- 
Chuck Noren
NET:     ncar!dinl!noren
US-MAIL: Martin Marietta I&CS, MS XL8058, P.O. Box 1260,
         Denver, CO 80201-1260
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