Random access memories (RAMs) are very widely used. There is no other kind of VLSI circuit with so many internal states: a one-megabit RAM has about 10315,(xx) internal states. Fortunately, the structure of a RAM is regular and its basic operation is fairly simple.

Due to the particular structure of a RAM, specific fault models for this kind of circuits have been derived. The main models and the corresponding test lengths are presented in Section 8.1 and in Section 8.2, respectively. The results are then extended to multiple faults and word-oriented memories in Section 8.3.

The power of random testing for RAMs is analysed and compared with deterministic testing in Section 8.4.