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The Cray X-MP was a supercomputer designed, built and sold by Cray Research. The company's first parallel vector processor machine and a fourth generation super, it was the 1982 successor to the 1976 Cray-1, and the world's fastest computer 1983–1985.

The principal designer was Steve Chen. The X-MP shared the ' horseshoe' design of the earlier machine. The processors ran on an 8.5  nanosecond clock (compared to 12.5 ns for the Cray-1A), delivering around 55  megaflops per processor and 235 megaflops for the four processor 1982 machine. The processors also had better chaining support, parallel arithmetic pipes, and shared memory access with multiple pipelines per processor.

The system initially ran the proprietary Cray Operating System (COS), with UniCOSUniCOS is the UNIX-like operating system of some Cray supercomputers, such as the X-MP and SV series. (a UNIX System V derivation) running through the guest operating systemIn computing, an operating system OS is the system software responsible for the direct control and management of hardware and basic system operations, as well as running application software such as word processing programs and web browsers. In general, t facility. UniCOS became the main OS from 1984 onwards.

The X-MP was sold with one, two, or four processors and from one to sixteen megawords (8–128  MBA megabyte is a unit of measurement for computer storage, memory and information; while its exact definition varies, it is in theory equal to one million bytes. The symbol for megabyte is MB (note B for Byte, lowercase b would mean bit). Three definitions) of RAM main memory (while initial memory capacity was limited to 16 megawords with a 24-bit address register, the extended memory architecture upgrade raised addressable memory to a theoretical 2  GBA gigabyte (symbol GB is a unit of measurement in computers of one thousand million bytes (the same as one billion bytes in the short scale usage). However, because computers work on the binary system, rather than a gigabyte being 103 Megabytes (1000 MBs)). A 1982 X-MP/48 was about US$The United States dollar is the official currency of the United States. It is also widely used as a reserve currency outside of the United States. Currently, the issuance of currency is controlled by the Federal Reserve Banking system. The most commonly u15 million plus the cost of disks.

The Cray-2 , a completely new design, was introduced 1985. A very different compact four-processor design with from 512 MB to 4 GB of main memory, it was clocked at 500 megaflops but was slower than the X-MP on certain calculations due to its high memory latency. In 1986 an X-MP/48 achieved a speed of 713 megaflops on the standardized LINPACK tests.

The X-MP-succeeding Cray Y-MP series was sold from 1988; no radical design, it was an evolutionary improvement of the X-MP with a new processor and the capacity for up to sixteen.