The smallest implementation of full chess is an irrelevant question. It all depends on the underlying machine and how the instructions are designed. At one extr

The smallest implementation of full chess is an irrelevant question. It all depends on the underlying machine and how the instructions are designed. At one extreme, a closed circuit with no programming interface but with the ability to play chess is a chess implementation with code size 0. A legitimate and interesting question is what is the smallest possible chess implementation in a particular instruction set architecture such as x86. A comparable example is writing quines (a program that outputs its own source code without reading itself from a file). It is a badge of honour to write the shortest quine in a particular programming language but comparing the length of a python quine implementation to a Java implementation is pretty meaningless.