Comparative Terminal Realizations with Alpha-Geometric Coding

The introduction of videotex services in several countries has spurred the search for the lowest cost user terminal which will provide acceptable performance. This has led to many arguments on the quality of graphics required. One faction argues that videotex is basically an alpha-numeric information service and only limited block graphics are required to enhance the text. The other faction argues that good graphics are an essential part of a videotex information service and are required to effectively communicate the information. Because of the wide range of information to be provided by videotex services it is likely that both faCtions are correct and in fact a wide range of terminals will be required. In the opinion of the authors of this paper, the graphics coding scheme used for videotex services should be capable of accommodating these variable terminal requirements and permit a maximum cf independence between the terminal, the communications medium used, and the data bases. In other words, a single data base should be capable of serving terminals with a variety of graphics qualities over a variety of communications mediums without any need for special processing for any particular terminal.