Kendall Square Research (KSR) was a supercomputer company headquartered originally in Kendall Square in Cambridge, Massachusetts in 1986, near MIT. It was co-founded by Henry Burkhardt III, who had previously helped found Data General and Encore Computer and was one of the original team that designed the PDP-8. KSR produced two models of supercomputer, the KSR1 and KSR2.
KSR instructions were of 6 types: memory reference (load and store), execute, control flow, memory control, I/O, and inserted. Execute instructions included arithmetic, logical, and type conversion. They were usually triadic register in format. Control flow refers to branches and jumps. Branch instructions were two cycles. The programmer (or compiler) could implicitly control the "quashing" behavior of the subsequent two instructions that would be initiated during the branch. The choices were: always retain the results, retain results if branch test is true, or retain results if branch test is false. Memory control provided synchronization primitives. I/O instructions were provided. Inserted instructions were forced into a flow by a coprocessor. Inserted load and store were used for DMA transfers. Inserted memory instructions were used to maintain cache coherency. New coprocessors could be interfaced with the inserted instruction mechanism. IEEE standard floating point arithmetic was supported. Sixty-four 64-bit wide registers were included.
In the KSR design, all of the memory was treated as cache. A Harvard style, separate bus for instructions and memory was used. Each node board contained 256 kB of I-cache and D-cache, essentially primary cache. At each node was 32 MB of memory for main cache. The system level architecture was shared virtual memory, which was physically distributed in the machine. The programmer or application only saw one contiguous address space, which was spanned by a 40-bit address. Traffic between nodes traveled at up to 4 gigabytes per second. The 32 megabytes per node, in aggregate, formed the physical memory of the machine.
Specialized input/output processors could be used in the system, providing scalable I/O. A 1088 node KSR1 could have 510 I/O channels with an aggregate in excess of 15 GB/s. Interfaces such as Ethernet, FDDI, and HIPPI were supported.
KSR refocused its efforts from the scientific to the commercial marketplace, with emphasis on parallel relational databases and OLTP operations. It then got out of the hardware business, but continued to market some of its data warehousing and analysis software products.
The first KSR1 system was installed in 1991. A few of the KSR1 models were sold, but as the KSR2 was being rolled out, the company collapsed amid accounting irregularities involving the overstatement of revenue.
One customer of the KSR2, the Pacific Northwest National Laboratory, a United States Department of Energy facility, purchased an enormous number of spare parts, and kept their machines running for years after the demise of KSR.
KSR, along with many of its competitors (see below) went bankrupt during the collapse of the supercomputer market in the early-1990s. KSR went out of business in late 1993.