stalker%capvax.decnet@CAPSRV.JHUAPL.EDU ("CAPVAX::STALKER") (07/20/90)
Dear Netters:
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VIRTUAL CHANNEL EXECUTIVE
The Virtual Channel Executive (VCX) is a low overhead operating
environment which provides transparent interprocessor communications. The
VCX has been designed to execute concurrently with other application programs
in a network of transputers. Basically, VCX provides variable length message
passing capabilities between application programs executing in different
transputers, giving them unlimited number of virtual channels for communica-
tions.
The main purpose of VCX is to free the application programmer from the
tedious and error prone task of designing point-to-point message passing
algorithms for interprocessor communications. Designing, implementing, and
testing these algorithms can be quite a challenge, even when the number of
processors is small. A great deal of effort must be invested to ensure
deadlock-free communications. In addition, deciding which is the best path to
route the data can be a tiresome and error prone process, even if the network
has a handful of processors.
With our method, application programs in different transputers
communicate with each other through their local VCX's via soft-channels.
The VCX's work as an interface between two application programs and use the
transputer links to route the data from one processor to another. The routing
of data is assisted by two look-up tables; one table defines the connectivity
of the application programs while the other maps the communications through
the physical network. The program connectivity table is supplied by the
application programmer while the other table is generated off-line by a
supporting software tool. This off-line Routing Table Generator tool will
find all possible paths from every transputer to all the others in the
network. It will also rank these paths from shortest to longest and eliminate
any cyclic paths encountered.
A fully connected group of transputers offers the possibility of many
different virtual network configurations (i.e. pipeline, mesh, toroid, tree,
hypercube, etc.). With VCX, a network can be booted with one of these virtual
configurations and then dynamically reconfigure with a different one. This
on-the-fly virtual reconfiguration capability offers many possibilities:
dynamic network tuning, fault tolerant communications, dynamic allocation/
partition of computing power, etc.
The Virtual Channel Executive is written in the "C" language, targeted
for the Logical System compiler Version 88.4. Since the major portion of the
code is written in the standard "C" language, it should be simple to port VCX
to other transputer "C" compilers. In addition, VCX can be rewritten in other
high level languages (Ada, FORTRAN, OCCAM, PASCAL, etc.) with a reasonable
amount of effort.
>>>> VCX RELEASE IS EXPECTED IN EARLY FALL 1990 <<<<
For more information contact: Mario D. Stalker
SYSCON Corporation
9841 Broken Land Pkwy, Suite 210
Columbia, Maryland 21046
Telephone: (301) 381-8319
FAX: (301) 381-8321
E-Mail: stalker@capsrv.jhuapl.edu
_____________________________________________________________________________
| |
| SYSCON Corporation, a subsidiary of Harnischfeger Industries, Inc. |
| Corporate Headquarters |
| 1000 Thomas Jefferson Street, N.W. |
| Washington, D.C. 20007 |
| |
| System Engineering, Computer Systems, Training and Simulation Systems, |
| Facilities Management, Technical Services, Hardware/Software Products. |
| |
| Parallel Processing Architectures, Real Time Programming, Software Tools |
| Development, X-Windows, Graphic Tools Developments. |
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