Complex sentence: USR was one of the first companies to offer high-speed dialup modems for personal computers, inventing its proprietary HST (High-Speed Transfer) protocol as a less-expensive alternative to the industry-standard v.32 family of protocols.
Split into simpler sentences: USR was one of the first companies to offer high-speed dialup modems for personal computers. The company invented a proprietary protocol named HST (High-Speed Transfer) as a less-expensive alternative to the industry-standard v.32 family of protocols.