VAX REAL-TIME ACCELERATOR SOFTWARE, Version 2.0A		SPD 29.43.02

DESCRIPTION
                          
VAX REAL-TIME ACCELERATOR SOFTWARE (VAX RTA) is a VMS layered product that 
integrates the VAXELN message passing capability with VMS Operating System 
software.

With VAX RTA and the VAXELN Toolkit, users develop realtime applications 
that can be distributed between the VMS host processor and the VAXELN-based 
KA800 processors.

VAX RTA enables the VMS host processor to control the VAXELN realtime 
processors using either program control or through a command language 
interface.   VAXELN-based KA800 processors communicate with the VMS host 
and each other at DMA speeds over the the VAXBI bus.  Communication between 
processors occurs via standard VAXELN message passing services and the VAX 
RTA runtime library procedures.

VAX RTA runs on the VMS Operating System and supports the KA800 realtime 
processor running VAXELN.

Features

VAX RTA improves overall system performance by putting the computing power 
closer to the realtime event that is being controlled or monitored.  This 
can reduce interrupt overhead and increase the predictability of time 
critical operations. 

The impact of an intensive operation on the VMS host system can be reduced 
and even eliminated by distributing realtime data handling to dedicated 
VAXELN VAX RTA processors. 

Communication between processors occurs using high speed DMA transfers. VAX 
RTA communication services are the same for both VMS and VAXELN 
applications. VAXELN ports, messages, and the local name service are 
implemented under VAX RTA.
                                     
Each realtime processor has its own local memory for the application 
program, increasing available memory for the VMS system and increasing the 
performance of the realtime processor. 

Realtime applications are developed and debugged using the standard VAXELN 
Toolkit.  VAXELN applications, including device drivers, can be developed 
entirely in a high level language.

HARDWARE REQUIREMENTS

VAX configuration as specified in the System Support Addendum (SSA 
29.43.02-x).

SOFTWARE REQUIREMENTS*

Operating System
                  
VMS Operating System

Layered Products

VAXELN Toolkit

A VAXELN Toolkit is required to develop a VAX RTA application.

*   Refer to the System Support Addendum  (SSA 29.43.02-x) for availability 
    and the required version of prerequisite/optional software.
 
ORDERING INFORMATION

Software Licenses: QL-VJNA*-**
Software Media: QA-VJNA*-**
Software Documentation: QA-VJNAA-GZ
Software Product Services: QT-VJNA*-**

*   Denotes variant fields. For additional information on available 
    licenses, services and media, refer to the appropriate price book.

SOFTWARE LICENSING

A VAXELN Runtime License is included with each KA800 VAX RTA processor.

This software is furnished under the licensing provisions of Digital 
Equipment Corporation's Standard Terms and Conditions. For more information 
about Digital's licensing terms and policies, contact your local Digital 
office. 

LICENSE MANAGEMENT FACILITY

This product supports the VMS License Management Facility (LMF).  License 
units for this this product are allocated on a CPU-capacity basis.  

For more information on the License Management Facility, refer to the VMS 
Operating System Software Product Description (SPD 25.01.xx) or the License 
Management Facility Manual of the VMS Operating System documentation set.

For more information about Digital's licensing terms and policies, contact 
your local Digital office.

SOFTWARE PRODUCT SERVICES

A variety of service options are available from Digital.  For more 
information contact your local Digital office. 

SOFTWARE WARRANTY

Warranty for this software product is provided by Digital with the purchase 
of a license for the product as defined in the Software Warranty Addendum 
of this SPD.

(R)  The DIGITAL Logo is a registered trademark of Digital Equipment 
     Corporation.
(TM) VAX C, VAX FORTRAN, MicroVAX, VAX, and VAXstation are trademarks of 
     Digital Equipment Corporation.

February 1990
AE-LS83C-TE