HIARCS is a proprietary UCI chess engine developed by Mark Uniacke. Its name is an acronym standing for higher intelligence auto-response chess system. Because Hiarcs is written portable in C, it is available on multiple platforms such as Pocket PC, Palm OS, PDAs, iOS, Microsoft Windows and Mac OS X.HIARCS opening book authors over time were Eric Hallsworth, Sebastian Böhme and Harvey Williamson, who is also operating HIARCS regularly at various computer chess tournaments.