Mtops (million theoretical operations per second) is a measure of computer performance used by the U.S. government and cooperating countries in determining whether a computer can be exported abroad to certain countries that might use it for nuclear arms development. (Mtops sometimes is written as "MTOPS" or "mtops.")
In early November 1997, the U.S. Congress included in its 1997 Defense Appropriation bill an amendment to subject any manufacturer of computers in the 2,000 to 7,000 Mtops range to licensing restrictions on sales to many countries that have not agreed to stop nuclear arms development or testing. These include China, Russia, and India. Computers in the 2,000 Mtops range include workstation and may soon include powerful personal computers. The computer technology industry argued that computers in this range are already widely manufactured and sold abroad, even in a number of countries on the restricted list, and that the law would make it difficult for U.S. computer manufacturers to compete with other countries. While the law, which went into effect on February 2, 1998, doesn't prohibit the shipment of computers in these classes to the designated "tier 3" countries, application for permission to ship can take up to 90 days.
The calculation of Mtops involves counting the number of operations that could be performed by the computer during a second's time, based on a specified formula. The actual number of operations that any computer performs over a given period of time depends on which operations are performed (some operations take longer than others or can be performed within the same clock cycle with other operations) and the real cycle speed.