In one of the still remarkably rare examples of collaboration between STC and its ICL subsidiary, STC Defence Systems Ltd has won the first order to supply its ISL 50 fibre optic local area network, in a contract worth UKP500,000 with the Royal Armaments Research and Development Establishment, RARDE, in Fort Halstead. The ISL 50 operates at 50Mbps, supporting 1,000 peripherals and simultaneous access to data for up to 2,400 users. It is a distributed star network, using token passing to distribute data around the network. The core optical switching kit, called the portswitch, is based on ICL’s Macrolan, which is the high speed optical bearer used in the ICL Series 39 processor. The market for the ISL 50 is in medium-to-large local area networks – the system is only cost effective over 150 terminal connections. STC claims that the cost per terminal of fibre optic networks compare favourably with the average UKP500 per terminal cost of coaxial networks with the introduction of increasing competition in the market and as a result of standardisation. Is the ISL 50 project evidence of increasing convergence of marketing and product development between STC and ICL? Marketing manager at STC Defence Systems John Watson thinks it is, and particularly so in defence. STC will sell ISL 50 into the defence sector while ICL Defence Region at Winnersh, Berkshire will incorporate the system into its networking products for the commercial market. Kenneth Bacon was recently instated as chairman of STC Defence Systems to effect a joint position for the two companies on defence. The two hope the system will be equally attractive in other applications, such as banking, where security is of prime importance, but for the moment interest is coming from the defence sector. The ISL 50 portswitch has six optical ports, which link to another port swich or to a network interface unit up to a mile apart. The network interface unit, based on an Intel 8086 processor, provides the interface to the network for hosts and users. It does the switching and is used in the polling of the access token and in broadcasting data. It offers synchronous X25 interfaces or up to 16 asynchronous V24 interfaces at up to 19.2Kbps for terminal access. Network management workstations for configuration management, fault diagnosis and performance monitoring are separately linked to the network. Further announcements are planned for the system, according to specific customers’ needs, including an upgrade in speed for the portswitch, which ICL is developing on the Macrolan, using STC components. Also under development at STC is an Ethernet interface for the system as well as capacity for concurrent voice and data transmission.