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<== Date ==> <== Thread ==>

Subject: Re: BITBUS and PC's
From: hill@luke.atdiv.lanl.gov (Jeff Hill)
Date: Thu, 9 Jun 94 15:54:39 MDT
 
> > Any comments about using PC's?
> 
> Every week I hear from someone wanting to use a PC as an IOC, either to
> preserve an existing hardware/software investment, or to take advantage
> of EISA boards that are cheaper than the equivalent VME board or that
> have no equivalent on an EPICS supported platform.  In fact, several
> APS-affiliated developers are talking about limiting their use of EPICS
> at APS to those features they can mimic on PC's at their home labs, so
> they can run approximately the same software in both places (a very big
> deal to many developers here).
> 
> Scary?  It reduces EPICS, in such applications, to small pieces of the
> channel-access library.  But I can't argue with someone solving their
> group's problems the only way they can.
> 
> What would it cost to port EPICS to VxWorks on a PC?
> 

The port would require changes to the CA server to swap the bytes in
each of the structures in db_access.h. Part of this code already
exists in the VAX CA client library. There is also some byte swapping
in the socket interface and the CA protocol that would need to be 
handled. You would also need to load your database in ASCII. If you wish 
to use existing EPICS drivers then be sure to pad uncertainty into the 
schedule for potential memory mapping problems and other CPU dependencies.
The above assumes that you will be using a VME SBC PC. If it
is to be an EISA IOC then there will be some drivers to write.

When WRS produced their first board support package for the i960
they were significantly behind schedule producing a working
system.

Jeff

______________________________________________________________________
Jeffrey O. Hill			Internet	johill@lanl.gov
LANL MS H820			Voice		505 665 1831
Los Alamos, NM USA 87545	FAX		505 665 5107

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