Michael Purser

COSINE Sub-Project P8: security services

Abstract COSINE Sub-Project P8, with its limited but attainable goals of secure E-Mail and secure remote access, supported by a Certification Authority and public key cryptographic functions, is intended to demonstrate that these functions can be provided in a relatively short time, and serve a very useful purpose. It is hoped that the project will itself extend to more users and possibly to more services in the future. It is intended to provide practical experience for other more ambitious projects.

Multitasking across a LAN for communications switching

Abstract A multitasking executive usually forms the kernel or nucleus of most real-time systems. The essential functions of the executive may be summarized as: scheduling of tasks; interrupt handling; provision of intertask primitives and other systems primitives. These foundations can be used to construct powerful systems with elaborate device drivers, handling for example backing-store, or high-speed communications links.

The PHS protocol

The paper presents a simple single layer protocol covering the functions of X25 levels 2 and 3. It can be used on synchronous or asynchronous lines, such as employed for normal computer terminals. It requires no special hardware, and can use the standard device driver software supplied by manufacturers. The protocol has been working successfully for over two years, and could be of interest to networking projects with limited resources.

As We Saw It: The Context of the Life of George Francis Fitzgerald

Drawing on the traditions and perspectives of the authors own family and relatives, which included George Francis Fitzgerald, the society in which this notable physicist lived and worked in the late nineteenth century is sketched.

Implementing and proving security services for the RARE/COSINE community

Abstract Secure electronic mail (PEM) and remote access services, using asymmetric key cryptology have been developed and proved between several European countries. The paper reviews the project, high-lighting its shortcomings, since they are most likely to be of interest to others.

X.25—the fulcrum for network standardization

Abstract The synchronous interface to packet switched data networks defined by the CCITTs X.25 recommendation has been in practical use for approximately ten years. Conceived and introduced amidst controversy, it has, despite its defects, more than stood the test of time. The recommendations early history is briefly outlined, followed by a review of its development to the present day in some detail. In a wider context, the international acceptance of the standard has, in turn, contributed greatly to the success of packet switching. This wider influence is also discussed, as is the influence of X.25 in other related areas, whether Common Channel Signalling (CCS), Integrated Services Digital Networks (ISDN), Asynchronous Time-Division Switching (ATDS) or the whole Open Systems Interconnection Reference Model. X.25 is the fulcrum which has enabled the telecommunication administrations of the world to lever the computer manufacturers and users into ever greater conformance to international standards in all aspects of data networks.

The design of a small packet-switching

Abstract This paper discusses the design of a packet-switching node which handles virtual circuits. Particular reference is made to the switching nodes capacity and loading. It is shown that the switch and its associated communications links can be dimensioned to handle offered traffic, using techniques borrowed from the telephone network.

Systems programming for data communications on minicomputers

This paper examines some of the special considerations which apply to the development of such software for minicomputers. These are treated under the following general categories: loading and throughput the external interfaces of the system software the internal structure of the system software developing the software .