(Tandem Computers Inc., Cupertino, CA) A former major manufacturer of fault-tolerant computers founded in 1974 by James Treybig and provider of the early 21st century technology for HP's enterprise computing strategy. Tandem was the first company to address the transaction processing (OLTP) market for online reservations and financial transfers by providing computers designed from the ground up for fault-tolerant operation. These computers are used in all the major banks, stock exchanges, credit card companies and ATM machines in the world.

Tandem's most significant product was its MIPS-based Himalaya series which ran the NonStop Kernel operating system, compatible with Tandem's Guardian OS. This platform lives on in the NonStop S-series servers from HP, which acquired Tandem's technology via Compaq in 2002. Compaq had purchased Tandem in 1997.