Having laid plans to spin off its worthy but most boring chip lines as Fairchild Semiconductor Inc, National Semiconductor Corp is taking steps to add to its portfolio of parts. It has agreed to acquire Mediamatics Inc, a Fremont, California developer of software and chips for video and audio functions. NatSemi is to pay 3.4 million new shares for the company, giving an indicated value for the deal of around $99.8m. NatSemi says it wants the company to accelerate its entry into the home entertainment market for technologies such as disk-based video players and digital set-top boxes. Fairchild Semiconductor is being sold to a group combining its management with the Sterling LLC venture capital arm of Citicorp, in a deal valued at some $550m.