Up to that point all Royal Navy (RN) ships and submarines had command systems built by Ferranti using custom-built electronics and specialised proprietary processors.
In a departure from previous practice, which had favoured 'preferred contractor' policies, the competition was won by a new company called Gresham-CAP, leading a consortium of Gresham-Lion (now part of Ultra Electronics plc) and CAP Scientific.
The consortium proposed a novel distributed processing system based on commercial off-the-shelf (COTS) processors, with a modular software architecture largely written in the Ada programming language.
In the initial phase equipment fitted to the Vanguard-class submarines most processing is done by Intel 80386 single-board computers, each with its own Ada run-time environment.
The essence of the problem was the need to map the Ada tasking environment to the run-time model of UNIX processes in a way which preserved SMCS' real-time characteristics enough to maintain dependability.
In its last major Defence Review, as reported in 2003,[6] the UK Parliament agreed numerous improvements for RN submarines, but no changes to the Vanguard boats or the Trident missile system.
In 2002, it was proposed to convert SMCS to run on standard PC x86 hardware, albeit in rugged industrialised form, for naval command systems.
Assuming Gates' testimony to be true, these 'pro-UNIX' engineers felt that open-source UNIX, rather than Microsoft Windows, should be used as the foundation of future naval command systems and circulated their concerns within the company.
[citation needed] Having developed SMCS-NG as an internal project, BAE Systems independently proposed to the MoD that the original SMCS equipment be replaced by its own, newer, version.
After sea trials in HMS Torbay, the MoD awarded contracts to BAE Systems[13] for refit of SMCS-NG into most RN submarines, including the Vanguard fleet.
Although the Defence Minister Adam Ingram told the UK Parliament in October 2004 that no decision had been made about conversion of the Vanguard fleet to run SMCS-NG,[14] the MoD placed the contracts the following month.