The Orion was a series of 32-bit super-minicomputers designed and produced in the 1980s by High Level Hardware Limited (HLH), a company based in Oxford, UK. The company produced four versions of the machine: The original Orion, sometimes referred to as the "Microcodeable Orion". The Orion 1/05, in which the microcodeable CPU was replaced with the much faster Fairchild Clipper RISC C-100 processor providing approximately 5.5 MIPS of integer performance and 1 Mflop of double precision floating point performance. The Orion 1/07 which offered approximately 33% greater performance over the 1/05 (7.3 MIPS and 1.33 Mflops). The Orion 1/10 based on a later generation C-300 Clipper from the Advanced Processor Division at Intergraph Corporation that required extensive cooling. The Orion 1/10 offered a further 30% improvement for integer and single precision floating point operations and over 150% improvement for double precision floating point (10 MIPS and 3 Mflops). All four machines employed the same I/O sub-system. Background High Level Hardware was an independent British company formed in early 1982 by David G. Small and Timothy B. Robinson. David Small was previously a founder shareholder and director of Oxford-based Research Machines Limited. Both partners were previously senior members of Research Machine's Special Projects Group. In 1984, as a result of that research, High Level Hardware launched the Orion, a high performance, microcodeable, UNIX superminicomputer targeted particularly at scientific applications such as mathematical modeling, artificial intelligence and symbolic algebra. In April 1987 High Level Hardware introduced a series of Orions based upon the Fairchild Clipper processor but abandoned the hardware market in late 1989 to concentrate on high-end Apple Macintosh sales. Microcodeable Orion The original Orion employed a processor architecture based on Am2900-series devices. This CPU was novel in that its microcode was writable; in other words, its instruction set could be redefined. This facility was used to customise some Orions with instruction sets optimised to run the Occam and LISP programming languages or even to compute fractals. The central processing unit The CPU consisted of an ALU that was built around the Am2901 bit-sliced microprocessor. To this a byte manipulation unit was added which could perform the shifting, rotating and masking operation required for handling eight and sixteen bit data. Additional logic was provided to support both signed and unsigned two's complement comparisons in a single operation, multiple precision arithmetic and floating point normalization. Most operations could be performed in 150