which was a successor to the CDC 1700 minicomputer. It was mostly used in real-time environments. One noteworthy application is as the basis of the 2550—a communications processor used by CDC 6000 series and Cyber 70/Cyber 170 mainframes. The 2550 was a product of CDC's Communications Systems Division, in Santa Ana, California (STAOPS). STAOPS also produced another communication processor (CP), used in networks hosted by IBM mainframes. This M1000 CP, later renamed C1000, came from an acquisition of Marshall MDM Communications. A three-board set was added to the Cyber 18 to create the 2550. The Cyber 18 was generally programmed in Pascal and assembly language; FORTRAN, BASIC, and RPG II were also available. Operating systems included RTOS (Real-Time Operating System), MSOS 5 (Mass Storage Operating System), and TIMESHARE 3 (time-sharing system). "Cyber 18-17" was just a new name for the System 17, based on the 1784 processor. Other Cyber 18s (Cyber 18-05, 18-10, 18-20, and 18-30) had microprogrammable processors with up to 128K words of memory, four additional general registers, and an enhanced instruction set. The Cyber 18-30 had dual processors. A special version of the Cyber 18, known as the MP32, that was 32-bit instead of 16-bit was created for the National Security Agency for crypto-analysis work. The MP32 had the Fortran math runtime library package built into its microcode. The Soviet Union tried to buy several of these systems and they were being built when the U.S. Government cancelled the order. The parts for the MP32 were absorbed into the Cyber 18 production. One of the uses of the Cyber 18 was monitoring the Alaskan Pipeline. Cyber 1000 The M1000 / C1000, later renamed Cyber 1000, was used as a message store and forward system used by the Federal Reserve System. A version of the Cyber 1000 with its hard drive removed was used by Bell Telephone. This was a RISC processor (reduced instruction set computer). An improved version known as the Cyber 1000-2 with the Line Termination Sub-System added 256 Zilog Z80 microprocessors. The Bell Operating Companies purchased large numbers of these systems in the mid-to-late 1980s for data communications. In the late 1980s the XN10 was released with an improved processor (a direct memory access instruction was added) as well as a size reduction from two cabinets to one. The XN20 was an improved version of the XN10 with a much smaller footprint. The Line Termination