This paper introduces a space bounded alternating one-way multihead Turing machine with only universal states, and investigates fundamental properties of this machine. We show for example that for any function L such that [L(n)/n]0, (1) there is a set in [U2-HTM(0)], but not in [Nk-HTM(L(n))], and there is a set in [N2-HTM(0)], but not in [Uk-HTM(L(n))], (2) for each k1, [Uk-HTM(L(n))][U(k+1)-HTM(L(n))], and (3) [Uk-HTM(L(n))][Nk-HTM(L(n))][Dk-HTM(L(n))], where [Uk-HTM(L(n))] denotes the class of sets accepted by L(n) space bounded alternating one-way k-head Turing machines with only universal states, and [Nk-HTM(L(n))]([Dk-HTM(L(n))] denotes the class of sets accepted by L(n) space bounded nondeterministic (deterministic) one-way k-head Turing machines.