https://ir.unisa.ac.za/handle/10500/23874 2026-05-07T12:10:28Z https://ir.unisa.ac.za/handle/10500/23934 Opening address: Vth SA Computer Symposium Viljoen, HC You may know that I am sitting on two chairs at the present moment: one, at the University of Stellenbosch in the Chair of Electronic Engineering as Dean of Engineering; the other at the SABC as chairman of the Board of Control. (The latter is a chair known to have a built-in hot seat.) At both places, considerable advances in the area of computer technology were made in the recent past, and you will excuse me if I refer to both organisations this morning. 1990-01-01T00:00:00Z https://ir.unisa.ac.za/handle/10500/23933 Data structuring via functions Venter, BH A programming language data model is introduced, based on the notions that variables are functions and types are sets of values. It is shown that, despite the simplicity of the underlying mathematical formalism, the data model is very expressive, and does not violate basic intuitions about variables and types. 1990-01-01T00:00:00Z https://ir.unisa.ac.za/handle/10500/23932 An Estelle compiler for a protocol development environment Kritzinger, PS; van Dijk, J The development of communication protocol standards has been accompanied by the standardization of formal specification languages to describe these standards in a clear and unambiguous way. Simulta­neously, techniques for the performance analysis of protocols and their validation have been proposed. This paper describes experience with the development of a compiler for one such specification language, Estelle. The compiler forms part of a comprehensive protocol development environment. Apart from a brief description of the functionality provided by this environment, aspects of Estelle which influenced the design of the compiler are described as well as salient aspects of the compiler itself. 1990-01-01T00:00:00Z https://ir.unisa.ac.za/handle/10500/23930 On the generation of permutations Naccache de Paz, D A new incremental algorithm for generating permutations on 1,2,..n (hereafter called "arrangements') is presented. The scheme generates arrangement k +1 by reversing a certain prefix of its predecessor and linking it to the remaining unchanged part of k. The average size of this prefix tends very rapidly to 1 as n increases, and is equal to 37/30= 1,233... in the worst-case (where n=5). The proposed algorithm uses only elementary CPU operations (namely register-shifts, additions and tests - no multiplications are made) which makes it suitable for low level language implementation and saves time. A final interesting property is the possibility of compressing the results into an array of 1!+2!+..+n! digits, instead of the nn! memory cells normally required for saving all the n! arrangements on n elements. 1990-01-01T00:00:00Z