Experimental Physics and
Industrial Control System

[email protected] (Carl W. Cork) · Thu, 16 Jun 94 13:32:40 PDT

Gerry Swislow writes:

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I am certainly naive as to the real-time requirements of EPICS, but maybe  
one system to consider as a target for porting is something like the Venix  
real-time operating system.  Unlike Vx-works and Lynx, Venix is a real UNIX  
SYSVR4.2 operating system.  It's only for Intel x86, but that does mean the  
hardware is cheap and common.  As it is real UNIX, the development  
environment is familiar and one can easily support non-epics VME modules  
with simple C programs on the same processor.  

Features of Venix from its brochure include:

fully preemptible kernel
bounded context switch latencies
fixed priority scheduling
contiguous file system
asynchronous and overlapped I/O
direct physical and I/O memory access
high speed RAM buffering
high resolution alarms (100hz to 10,000hz)
user space interrupts
memory locking
memory preallocation
etc.

The price is something like that for SCO UNIX, say 1-3K, depending on  
whether the software development bits are included, etc.  I'll have the  
brochure and programming manual at the meeting next week if anybody is  
interested.  The company's phone number is 617-661-1230 if somebody is real  
interested.  (My only interest in this is the preference for having a UNIX  
system running EPICS, rather than dealing with VX-works/OS-9/Lynx, etc.)

Gerry Swislow
-  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  - -
Certified Scientific Software  Internet : [email protected]
PO Box 390640                     Phone : +1 (617) 576-1610
Cambridge, MA  02139                Fax : +1 (617) 497-4242

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Just wanted to clarify one point about LynxOS:

LynxOS is as real a UNIX as Venix. Moreover it is Posix4.- compliant,
fully threaded, and supports multiprocessing. It runs on almost all of
the same platforms as are currently used by EPICS, as well as on
the 386...586 platforms.

I tested a loosely coupled multiprocessing version (Lynx calls it
snuggly coupled) using Motorola MVME147's and found the environment
and performance to be quite good. Thread context switching was only
slightly slower than VxWorks 'task' switches, and yet the
system was self hosting and supported true virtual memory. Almost
all of the GNU software compiles under this OS and it supports
X-Windows and also both BSD socket and SVR4 stream network libraries.

I think that it would be a mistake to choose an OS that only
ran on the 386...586 platforms (Venix, QNX, etc). I think we should
select a multiplatform/multiarchitecture OS such as LynxOS, RT-MACH,
or CHORUS if at all possible.

Carl Cork

(when it is available).

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System