Robert D. Gaglianello

HPC/VORX: a local area multicomputer system

A system is described that combines the major strengths of local area networks and multicomputers, namely resource sharing over geographically significant distances and small communication latencies. The result is a new architecture called a local area multicomputer (LAM). The system that is described attempts to solve the seemingly incompatible needs of the two application domains by utilizing a high-capacity, low-latency interconnection network called the HPC supported by the VORX multiprocessor computing environment. For systems with hundreds of nodes, the network capacity is in the Gb/s range, and the latency for small messages is about 10 mu s. The HPC can connect resources located several kilometers apart. The VORX environment provides the necessary program development tools and resource management functions needed to experiment with distributed applications. Two applications are outlined to show the diverse uses for a LAM system and the status of an 80-node system that includes 70 adjunct processors and ten SUN 3 workstations/fileservers.<<ETX>>

A distributed computing environment for robotics

Meglos is a multiprocessor operating system that is ideal for real-time applications. It provides the user with a distributed programming environment for developing, running, and debugging application programs. Meglos allows a single application to span several processors. Further, unrelated programs may run independently of each other on the same processor. A simple, yet powerful, mechanism for communications between programs is provided. With the current hardware configuration, up to twelve Motorola 68000 Multibus computer systems and a DEC VAX host running the UNIX operating system can be connected via the S/NET interconnect. Meglos exhibits communications latencies of 750 μsec, sufficiently small for most real-time applications.

Efficient Multi-Resolution Multi-Stream Video Systems withStandard Codecs

The availability of international standards based video codecs for inexpensive platforms is reducing the cost of desk-top video systems to a level which makes their wide deployment possible. The current systems, however, are tuned for processing a single video stream only and their use in multiple video applications, such as continuous presence video teleconferencing and digital picture-in-picture, is difficult and inefficient. In this paper, we discuss two systems for efficient generation and display of multi-resolution, multiple compressed video material. Based on simple additions to standard codecs, both systems are capable of generating multiple bit streams corresponding to different resolutions of a single video source and they can decode such streams from multiple sources and display the resulting video sequences simultaneously. Both systems provide multiple video functionality to standard codecs with almost no extra memory or processing power requirements. Also, they make it possible for the users to customize the placement and size of their video windows, just as text and graphics windows can be manipulated.

Communications in Meglos

Meglos provides a user‐level, message‐based programming environment for a system of interconnected processors. It allows the simultaneous execution of a wide range of applications including real‐time control and large‐scale computations requiring the co‐operative work of many processors. The communications mechanisms in Meglos are designed to be easy to use and to provide high performance at the applications level. The communications primitives are based on symmetric, error‐resilient channels that are independently flow controlled. Two‐ended channels between pairs of co‐operating processes provide communications with low latency and high throughput. Multicast channels are used to send messages efficiently among a large group of processors in a single operation.

The Liaison network multimedia workstation

A description is given of a workstation architecture, Liaison, that solves the high bandwidth problem for real-time video and allows the exploration of these communications issues. By distributing the workstations intelligence over a high-performance network, both the computation and communication load are shed to other processors on the network. The Liaison display performs only the low-level functions of acquiring and displaying images, whereas the remainder of the workstations functionality is performed by a pool of distributed processors. Initial experiences with this architecture using a prototype monochrome workstation have provided insight into the issues surrounding the control and processing of communications-intensive applications.<<ETX>>

The evolution of HPC/VORX

HPC/VORX is a computing system that provides closely coupled computing between large numbers of processors. It also supports the connection of many host workstations which may be geographically distributed within the area of a large building and allows a single applications to span many processors and many workstations. We relate some of the lessons that were learned while building and using HPC/VORX and in the transition to HPC/VORX from a smaller, less capable system. The problems that we encountered included difficulties in scaling resource managers and human interfaces to large numbers of processors, the design of communications primitives and protocols, and the implementation of programming abstractions.

Convergence of telephony and television: More than a computer on your TV

The ongoing convergence of Telephony with Television, specifically cable TV and/or IPTV opens possibilities for rich social interactions between groups of people. In this paper we will illustrate some of the unique ways that these groups may utilize the various telecommunication, telephony, and television resources available to them; providing a rich social and entertainment experience.

Communications-intensive workstations

The introduction of gigabit local area networks and the resultant proliferation of multimedia applications will require fundamental changes in the design of computer workstations. The workstation is implemented as a distributed application on a local area network in order to focus on communications issues. A single processor is dedicated to the low-level functions of acquiring image and audio streams from the network and sending keyboard and mouse information to the network. The display processor receives only bitmap images of data to be displayed. Higher level functionality, like that provided by the X-window system, is handled by other processors in the network. To demonstrate the feasibility of this architecture, a prototype monochrome (bilevel black and white) workstation was built that is able to simultaneously display several windows with 30 frame/s video, each arriving from a different processor via a local area interconnect. The feasibility of interleaving real-time video images across multiple disks on different processors to provide sufficient throughput for full-motion video is demonstrated. A simple method provides video and sound which are synchronized with each other and which flow smoothly.<<ETX>>

Developing applications for EBIF and tru2way

The ongoing convergence of Computers, Telephony and Television, along with an increasing interest by Cable MSOs in interactive applications, has created opportunities for developers to create interactive rich applications on a new set of platforms. The MSOs are basing their foray into interactive applications on industry standard platforms and environments. This paper provides an overview of the two main platforms (EBIF and tru2way) and discusses the implementation of an interactive application that will execute on both platforms. Implementing the same app on each platform will allow us to compare and contrast the differences between and limitations of the two standards. It is hoped that application developers will be interested in exploring these new platforms.

The HPC/VORX local area multicomputer system

The HPC/VORX system supports communication performance typically found in closely coupled parallel processors across significant geographic distances. With such a system it is reported to be possible to combine the two computer architectures, local area networks (LANs) and medium-grain multicomputers into a single unified system. The hardware consists of a high-capacity, low-latency interconnection network called the HPC capable of growing gracefully from systems with twelve nodes or less to systems encompassing thousands of nodes. The VORX multiprocessor computing environment provides program development tools and resource management functions for experimenting with distributed applications. An eighty-node system that includes ten SUN 3 workstations/fileservers and seventy adjunct processors has been running since October 1988.<<ETX>>