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(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 purchased Tandem in 1997. See ServerNet.

James Treybig
Treybig founded Tandem and was at its helm for more than 20 years. (Image courtesy of Tandem Computers Incorporated.)

NonStop Processing
Tandem was the first company to build fault-tolerant systems for the OLTP market. At the top is Tandem's first NonStop system in 1976. At the bottom is the K10000, a massively parallel server that can scale up to 4,000 processors. (Images courtesy of Tandem Computers Incorporated.)


An earlier clustering technology from Tandem that provided a high-speed interconnect architecture between subsystems in the mid-1990s. ServerNet I used switching technology to transfer data at 50 Mbytes/sec in both directions between CPUs, between I/O devices and between CPU and I/O. ServerNet II boosted speed to 125 Mbytes/sec. Originally used with Tandem's proprietary fault-tolerant computers, ServerNet became available for Windows NT clusters. See clustering, SAN and Tandem.

Tandem's ServerNet Interconnect
Used for both MPP applications and SMP clusters, this conceptual diagram shows how ServerNet interconnected a high-speed switch between CPUs and I/O subsystems. The CPUs are purple; the disks are orange, and the green pipes are the ServerNet mesh. See MPP and SMP. (Image courtesy of Tandem Computers Incorporated.)

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