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From: berger@datacube.UUCP
Newsgroups: comp.unix.questions
Subject: Re: real-time Unix Systems
Message-ID: <106500007@datacube>
Date: Mon, 24-Aug-87 00:48:00 EDT
Article-I.D.: datacube.106500007
Posted: Mon Aug 24 00:48:00 1987
Date-Received: Tue, 25-Aug-87 01:37:59 EDT
References: <2663@bobkat.UUCP>
Lines: 44
Nf-ID: #R:bobkat.UUCP:-266300:datacube:106500007:000:2185
Nf-From: datacube.UUCP!berger    Aug 24 00:48:00 1987


We have implemented a scheme where we  control our  "real time" image
processing  hardware with  a Sun  Workstation.   It has  to handle at
least 60Hz frame rate interrupts to dynamically  update the registers
of  our  image  processing  hardware.    We  did  this  by creating a
"programmable"  interrupt handler.   Our  user program  can send down
instructions to the driver to tell it what to do when it gets certain
interrupts.  

This was very specific for our hardware but it works very well.  What
I'd like to see in terms of evolution of  Unix would  be some ability
to  create  a  unix  kernel /  utility package  that is  tuned for an
application.    IE  the  ability  to  select  features,  options  and
utilities and then build a dedicated version with  just those things.
Thus you could create  embeded applications  with just  the amount of
baggage you need.  

The major goal of this is to have a target kernel that could possibly
be prommed and yet  the programmer  can expect  a c  runtime / system
environment that they are pretty used to.  

For PROM based embedded systems, we are currently using  OS-9 in such
a way, we mostly edit, cross-compile on our Unix systems and download
to our OS-9 systems.  OS-9 has some features that would be  nice in a
targetable  "Unix"  such  as shareable  libraries that  link with the
executables at run-time, executables and the  operating system itself
is promable, does not require an MMU, etc.  Once we have debugged the
software, we can burn it into PROM.  

We've  made  OS-9  look  as  much  as  possilbe  as  a  unix run time
environment.  Ideally we could be  cross compiling  to an environment
that had a POSIX compatable run time environment that maybe had a few
restrictions to allow it to be prommed and not require an MMU.  

It would also be nice to be able to attach interrupts to user code
and a standard way to map physical addresses into user space.


				Bob Berger 

Datacube Inc. Systems / Software Group	4 Dearborn Rd. Peabody, Ma 01960
VOICE:	617-535-6644;	FAX: (617) 535-5643;  TWX: (710) 347-0125
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