
PRODUCT NAME: VAX DECscan VMS and ELN Bitbus Drivers,       SPD 27.98.02
              Version 2.0

DESCRIPTION

The DECscan Product set provides a hardware and software link between the 
Q-bus series of MicroVAX processors (MicroVAX II, IVAX, MicroVAX 3000) and
the Intel Bitbus.  It allows for communication between users in a MicroVAX 
host and multi-dropped devices and software tasks running on those devices
(nodes) adhering to Bitbus protocol. 

The DECscan software consists of the following:

1. A MicroVAX VMS driver, along with a user-interface program, allowing the
   user  to  access  a  Bitbus  system  either  through  a  program  or 
   interactively, when using VMS as the operating system.
   The MicroVAX VMS user-interface provides the user with the ability to 
   configure the system and test its responses for calibration purposes.  
   With this functionality, VAX DECscan allows the user to obtain and 
   monitor real-time data.

2. A VAXELN driver, allowing the user the ability to build finished VAXELN
   systems, on any VMS Host system, using the VAXELN toolkit.
   The finished VAXELN system is then down-line loaded to MicroVAX target 
   systems, where it runs without the presence of another operating system. 
   VAXELN is especially suited to creating real-time applications in which
   the system response speed and predictability to external events
   is critical.

   The ELN target systems may be diskless and down-line loaded via Ethernet
   using DECnet services and protocols or permanently resident in the ELN
   target systems using erasable, programmable,read-only memories (EPROMs).

3. An 8044 cross-assembler and support utilities, allowing the user to
   develop application tasks, on the VMS Host system, to run on 8044-
   based Bitbus Nodes. When using the DECscan MicroVAX VMS Driver, these
   Remote node tasks are down-line loaded directly to and run on the Bitbus
   nodes.  When using the DECscan ELN driver, these remote tasks are
   included in the finished VAXELN system which is down-line loaded to the
   MicroVAX target system. The finished VAXELN system then down-line loads
   the remote Bitbus tasks to run on the Bitbus nodes.

All communication with the IBQ01 Bitbus Controller (Refer to Hardware 
Requirements) is done via driver calls. The DECscan MicroVAX VMS and the 
DECscan ELN drivers provide the standard operating system interface to the 
IBQ01 Bitbus Controller. All driver communications to Bitbus nodes remain 
active until a reply is received by the IBQ01 controller or a user-specified 
timeout condition is reached.

Both drivers and the IBQ01 controller support the BITBUS capability of
multiple concurrently active communication paths (serialized by the BITBUS
protocol).  Communication requests can be active to multiple BITBUS nodes
and multiple tasks within a BITBUS node at the same time, and will complete
asynchronously, independent of each other.  Multiple requests to the same
node/task pair will have only one active at a time on the BITBUS, the rest
being queued in the IBQ01 controller.

Each Bitbus node supports up to eight active tasks. 

Under the DECscan MicroVAX VMS driver, the user issues QIO calls directly or 
through the user-interface.  The QIO call invokes the DECscan MicroVAX VMS 
driver, which sends commands to the IBQ01 controller, followed by an interrupt.

Under the DECscan VAXELN driver, the user issues driver calls through the
subroutines provided. The VAXELN subroutines complete upon initiating the 
transfer. An asynchronous return mechanism is provided to inform the caller 
when the actual transfer has been completed.

Depending upon the nature of the command, the IBQ01 either responds
directly or transfers this command, via the Bitbus, to a node running
Bitbus protocol.  In the latter case, the node response is application
dependent.  When the command has been processed by either the node or the 
IBQ01, the IBQ01 sends response data to the host followed by an interrupt.  
The drivers check the response data against what was sent for consistency
and reports either success or the reason for failure.

By using the asynchronous driver completion mechanisms provided (e.g. QIO
in VMS) and writing custom tasks for certain third party BITBUS nodes,
users can potentially distribute much processing and reduce the load on
the MicroVAX.  For instance, I/O to multiple nodes may be simultaneously
pending.  The various tasks on these nodes might be set up to only respond
to the pending I/O when the results of special processing or alarms are
available.  The MicroVAX process in this case could merely wait for event
flags indicating the node/task response had occurred.  Routine data processing
and control could be handled in the nodes' tasks.

The DECscan VMS driver and the DECscan ELN driver will support up to eight
IBQ01 controllers per MicroVAX system.

INSTALLATION

Only experienced customers should attempt installation of this product.
DIGITAL recommends that all other customers purchase DIGITAL's Installation
Services.  These services provide for installation of the software product
by an experienced DIGITAL Software Specialist.

HARDWARE REQUIREMENTS

VAX, MicroVAX, or VAXstation configuration as specified in the System Support
Addendum (SSA 27.98.02-x).

SOFTWARE REQUIREMENTS *

VMS Operating System or MicroVMS Operating System

VAXELN Toolkit

For VAXELN Driver

The VAXELN Toolkit, V3.0 must be installed on the host which is to 
receive the DECscan VAXELN driver.  Refer to VAXELN Toolkit (SPD 
28.02.xx).

OPTIONAL SOFTWARE *

VAX DECscan VMS Software Tool Kit

* Refer to the System Support Addendum for availability and required versions of
  prerequisite/optional software (SSA 27.98.02-x).

ORDERING INFORMATION

Software License:  QL-VCJA*-**
Software Media: QA-VCJA*-**
Software Documentation: QA-VCJAA-GZ
Software Product Services: QT-VCJA*-**

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

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. 
                                                                  
SOFTWARE LICENSING

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

LICENSE MANAGEMENT FACILITY
  
This layered product supports the VMS License Management Facility.
License units for 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 VMS Operating System documentation set.
  
For more information on DIGITAL's licensing  policies, contact your 
local DIGITAL office.
  
SOFTWARE PRODUCT SERVICES 

A variety of service options are available. For more information on these or
other services, please contact your local DIGITAL office. 


August 1988
AE-KN30C-TE

