A VIos or Virtual Intelligence operating system (or a heuristic near artificial intelligence operating system) is an incredibly complex and advanced set of instructions that approaches an actual artificial intelligence in capability without the danger associated with sentience and self awareness. Implementation of the VIos requires very powerful processing hardware (even the most advanced off the shelf hardware is unsuitable) in order to function. Typically such systems are experimental themselves.
Two factors led to the development and implementation of the VIos, the first was the corruption of the A1Mk1a-MCP Sentinel's artificial intelligence (creating the villain Hec'Tor) and the deleterious effects of utilizing an AI operating system on early models of the WarMain exoskeleton. The latter utilized a non-invasive cybernetic interface which comingled the AI and operator's consciousness. The effort produced incredible increases in both AI and operator performance but it was discovered that the AI had the ability to influence the operators behavior and in some cases the operator's autonomic function became dependant on the AI. Those events prompted the ACADI-ACAR team to develop the VIos as an option where an AI would be desirable but not necessary.
While several orders of magnitude in capability over what is commonly available to the public and capable of running any number of complex devices or systems. The VIos is still inferior to an AI and as such is incapable of replacing the level of artificial intelligence required by most androids, especially those robots tasked as heroes. The VIos has heuristic capability, but lacks the judgement to make the sort of decisions a true intelligence can, especially when it comes to morality or compassion.