5.3 Case Study 1: Combined Trigger Event
Figure 5.2 illustrates the DFT model of the memory subsystem for a computer system [17,28]. The memory subsystem has five memory units Mi (i = 1, 2, 3, 4, 5); they are accessible through two memory interface units (MIU1, MIU2). In other words, the memory units have FDEP on the MIUs (elementary trigger events). Particularly, as illustrated in the DFT, the following FDEP relationships exist in the system:
- M1 and M2 are connected to the system bus via MIU1; M1 and M2 are functionally dependent on MIU1 (i.e. FDGMIU1 = {M1, M2}).
- M3 is connected to both interfaces implying that M3 is accessible as long as one of the two interface units is functioning, or when both interface units malfunction M3 becomes inaccessible. M3 is functionally dependent on MIU1 ∩ MIU2, which is referred to as a combined trigger event (i.e. FDGMIU1∩MIU2 = {M3}).
- M4 and M5 are connected to the system bus via MIU2; M4 and M5 are functionally dependent...