an improved hoc interpreter was included in eighth edition research unix in 1985, but it has not been generally adopted by commercial unix systems or by linux distributions. instead, the earlier calculator languages dc and bc have become widespread on those systems. hoc survived and continued to evolve as part of the plan 9 operating system. several improved versions of hoc were released as free software by bell labs and other individuals (see list below). hoc is used as the primary scripting language for the neuron simulator.