High Level Hardware Ltd has developed a C compiler specifically for its Clipper-based Orion 1/05 processor, with the help of compiler specialist Green Hills of California. The Oxford company claims that the C1/05 compiler performs all the general optimisations which make programs smaller and faster. Commonly used variables and parameters are kept in machine registers leaving memory space free. High Level says that referencing a variable in a register rather than in memory takes only one-third of the space and one-third of the referencing time. C1/05 also allows local variables to be accessed by a stack pointer instead of a frame pointer and frequently-used static addresses to be stored in registers. The company adds that unless a program needs less than 64Kb, addresses must be four bytes long and, if an address is used only twice in a function, it is faster and less-space consuming to load it into a register which High Level claims reduces most static references to one-third of the space and less execution time. High Level will be selling the compiler bundled with Unix for a price of around UKP1,200. The company has no plans to offer the compiler to other users of the Intergraph Clipper set.