We consider a set of users wishing to receive a service in an asynchronous distributed system. Such users declare their wishes and then wait to gain admittance to be served. Except for the initial transient period, at least one user must be waiting to be served, and the system should be as fair as possible for users. A procedure that ensures such a situation is called a turn function. It can be easily implemented in the asynchronous multi-writer/reader shared memory model. The turn function is useful to solve some problems concerning temporal orders within an asynchronous distributed system (e.g., the mutual exclusion problem and the k-exclusion problem). In this paper we propose an algorithm for the turn function that can be implemented in the single-writer/multi-reader shared memory model. Its implementation is simpler than the general method of simulating operations of multi-writer/reader shared variables by using a bounded concurrent time-stamp scheme in the single-writer/multi-reader shared memory model. We show the correctness of our algorithm and discuss its efficiency.