The 3B20D Processor & DMERT Operating System: 3B20D Craft Interface

The "craft interface" is that part of the 3B20D Processor that enables people to obtain status information and exert control over the system. To those not involved in telephony, the word "craft" may seem odd. It has traditionally been used to refer to the people who work in and around telephone switching offices performing various maintenance functions on the equipment. In this article, the term is used somewhat liberally to mean any person who interacts with the 3B20D to perform administrative and maintenance functions. The 3B20D's craft interface is a marked departure from previous systems developed at Bell Laboratories because it relies almost exclusively on video displays and keyboard controls instead of the key-lamp panels and teletypewriters usually found in the Master Control Center (MCC) of electronic switching systems. Status information is presented 383 visually as graphical displays and text messages on various terminals and printers. There is also a capability to provide audible status by connecting the 3B20D to an audible alarm circuit. System control is exerted primarily via a keyboard attached to the video display terminal, although the 3B20D also includes a separate power control panel for each major hardware unit. Another important enhancement lies in the ability to access and control all aspects of the system from remote locations such as Switching Control Centers (SCCs). In the past, remote access was obtained by "piggy-backing" data links onto the typewriter terminals in the telephone office and by connecting a telemetry unit to the key-lamp control panel.