The flowering of new computer architectures continues apace, and after the reduced instruction set computer comes the wide instruction word computer, courtesy of Multiflow Computer Inc of Branford, Connecticut. The start-up company, which was only prepared to drop teasing hints of its plans last autumn (CI No 557), has spent three years and $17.6m of venture capital developing its 64-bit Trace machine, the key feature of which is that it uses instruction words that are at least 256 bits wide, rising to 1,024 bits on the top model. Use of the wide instruction word means that each word in the set accomplishes seven, 14 or 28 operations, depending on the model. Use of very long instruction words – also called horizontal microcode, can lead to a very fast machine because it greatly reduces instruction decode time, but the set tends to be highly redundant. The Trace machine, which runs under enhanced Berkeley 4.3 Unix, is designed for compute-intensive Fortran and C applications, and the name derives from use of Trace Scheduling Compilers, where the compiler compensates for conditional jumps by trying to second-guess the program on where to jump. The entry Trace 7/200 model, available now, is claimed to run at 6Mflops using the Linpack benchmark, and to execute 14.195 Dhrystone MIPS; peak performance is rated at 30 Mflops. Priced at $300,000, it includes 16Mb memory expandable to 512Mb, and comes with VME input-ouput processor and disk controller with 512Mb drive, tape drive, terminal, and Fortran and Unix. Upgrading to the 14/200 model, which has a 512-bit instruction word, 14 operations per instruction, requires addition of two boards, and to the 28/200, with a 1,024-bit instruction word and 28 operations per instruction, four boards. The top two models are set for shipment this autumn. Trace machines are in beta test at Sikorski, Grumman and the US Supercomputing Research Laboratory.
