by U.S. and allied forces. Computer technologies BBN bought a number of computers in the late 1950s and early 1960s, notably the first production PDP-1 from Digital Equipment Corporation, on which it implemented the BBN Time-Sharing System (1962). Ray Tomlinson of BBN is widely credited as having invented the first person-to-person network email in 1971 and the use of the @ sign in an email address. BBN has had a very distinguished career in natural-language understanding, ranging from speech recognition through machine translation and more recently machine understanding of the causality of events and accurate forecasts for the Intelligence Advanced Research Projects Activity (IARPA). BBN's education group, led by Wally Feurzeig, created the Logo programming language, conceived by BBN consultant Seymour Papert as a programming language that school-age children could learn. Other well-known BBN computer-related innovations include Interlisp programming language, the TENEX operating system, and the Colossal Cave Adventure game. BBN also is well known for its parallel computing systems, including the Pluribus, and the BBN Butterfly computers, which have been used for such tasks as warfare simulation for the U.S. Navy. BBN also developed the RS/1, RS/Explore, RS/Discover and the Cornerstone statistical software systems, and played a pioneering role in the development of today's semantic web, including participating in the DARPA Agent Markup Language project and chairing Web Ontology Language standardization. Networking technologies BBN was involved in building some of the earliest Internet networks, including the implementation and operation of the ARPANET and its Interface Message Processors;, as well as SATNET, PRNET, MILNET, SIMNET, the Terrestrial Wideband Network, the Defense Simulation Internet, CSNET, and NEARNET. In the course of these activities, BBN researchers invented the first link-state routing protocol. BBN was a key participant in the creation of the Internet. It was the first organization to receive an Autonomous System Number (AS1) for network identification. ASNs are an essential identification element used for Internet Backbone Routing; lower numbers generally indicate a longer established presence on the Internet. AS1 is now operated by Level 3 Communications following their acquisition of BBN's Genuity internet service provider. BBN registered the bbn.com domain on 24 April 1985, making it the second oldest domain name on the internet. In addition, BBN researchers participated in the development of TCP, created the Voice Funnel, an early predecessor of voice over IP, helped lead the creation of the first email security standard, Privacy Enhanced Mail (PEM), chaired