A system for generating pseudorandom codes using a register which contains
an identification of the code tree leg of the desired code and a counter
which outputs a successive binary sequence. The output from the counter
is bit-by-bit ANDed with the output of the register, and those outputs
are XORed together to output a single bit. As the counter is sequenced,
each count results in a different bit that is output from the XOR gate,
resulting in the desired code.