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From: wwm@wa8tzg.mi.org (Bill Meahan)
Newsgroups: comp.unix.questions
Subject: Re: Real time unix?
Message-ID: <1991Feb1.002914.792@wa8tzg.mi.org>
Date: 1 Feb 91 00:29:14 GMT
References: <1991Jan30.235536.13416@cbnewsm.att.com>
Organization: What, ME Organized?
Lines: 30

In article <1991Jan30.235536.13416@cbnewsm.att.com> gregk@cbnewsm.att.com (gregory.p.kochanski) writes:
>Is there a real time unix which might allow me to read or write to a device
>in 50 microseconds or less?  To be more specific, I do experimental physics,
>and am basically poking around, looking at atoms on surfaces with a tunneling
>microscope.  This is an experiment where the software and hardware need to
>be closely coupled.  Basically, you read a word from a A-D converter,
>do a few computations, and output a word or two to a D-A converter.
>
>The computations are not stylized enough or simple enough to convenientlyy
>put in a device driver (and I'm not that masochistic, anyway).
>Are there unixes where this is possible?  Perhaps allowing a user
>program direct access to some hardware, and locking processes in the CPU?

Hewlett-Packard's flavor of UN*X, HP-UX, does indeed have many real-time
extensions.  The 50 microsecond requirement, however, is difficult for
even dedicated RTOS systems (e.g. MTOS, VRTX, etc.) to handle without the
appropriate hardware.

Check with your local HP rep.  There is supposedly a "real-time coprocessor"
board available for the 800 (RISC) boxes.  There is also a VME extension kit
for the 300 (680[34]0) series.


"I have no connection with HP other than being a satisfied (well, MOSTLY
satisfied) customer."
-- 
Bill Meahan (WA8TZG)             |   Programming is simple:
wwm@wa8tzg.mi.org  OR            |
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