MS-DOS Prolog implementations revisited

In an earlier article [11] we proposed a taxonomy for classification of PROLOG implementations. This analysis has been used by ourselves [1], [3], [11] and others [6] in evaluation of current microcomputer-based products. However, it has become out of date for several reasons. First, PROLOG has matured to the point where the language kernels have become comparable in functionality. Thus, many of the features which distinguished products a few years ago no longer do so. Conversely, increasing attention is being paid to extra-and metalogical support, so that there are now features which are distinguishing which were not, only a few years back. It is now quite reasonable to expect a PROLOG implementation to support graphics, virtual memory, modularization, and so forth. Thus, we offer a revision which is more in keeping with the current PROLOG offerings.