Etcha is a two-dimensional descendant of Jeffry Johnston's BitChanger. Like BitChanger, it has four instructions; unlike BitChanger, its storage model is based on turtle graphics, which permits it to be immediately used for an alternative purpose: graphical composition. Unlike the turtle in LOGO however, the turtle in Etcha is an integral part of the computation, playing a role similar to the tape head of a Turing machine.
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tc.catseye.etcha in the Etcha distribution
- tc.catseye.etcha (the reference implementation), an interpreter in Java in the Etcha distribution
- tc.catseye.yoob.etcha, an interpreter in Java in the yoob distribution