A virtual terminal protocol based on the use of zones
D. L. A. Barber · ACM SIGCOMM Computer Communication Review · 1977
Companion papers have considered the concept of the Virtual Terminal in the context of a network (ref 1) and as an interface between users and computers (ref 2). These papers give a background for the present paper which proposes a Virtual Terminal protocol for use between an applications program and a remote terminal handler, based on the concept of the dynamic assignment of zones, introduced by Luca (ref 3). The paper by Luca contains an excellent discussion of the concept and use of zones, which seem well suited for a Virtual Terminal protocol although this was not considered in his paper. Some simplification of Luca's work is appropriate because he is concerned both with the interface between an application and the terminal handler, which he calls the programmable communications controller (PCC), and with the mapping between the PCC and a real terminal. The first aspect only will be considered here as the basis of a simple applications level protocol for a Virtual Terminal. However, Luca's paper is also a useful guide for the designers of the terminal handler and users who are concerned with mapping the Virtual Terminal onto particular real terminals. This paper draws on the ideas contained in the earlier papers reviewed in Appendix 1 of ref 2, and uses the notation introduced in Appendix 2 of ref 2. The zones concept is similar to the idea of the Communication Unit introduced by Schulze (ref 4) and this has also influenced the proposals set out below.