  We present the first explicit, and currently simplest, randomized algorithm
for 2-process wait-free test-and-set. It is implemented with two 4-valued
single writer single reader atomic variables. A test-and-set takes at most 11
expected elementary steps, while a reset takes exactly 1 elementary step. Based
on a finite-state analysis, the proofs of correctness and expected length are
compressed into one table.
