1. Substitution Conclusion for the 71V65703S85BQGI From a core specification and package perspective, the 71V65703S85BQGI can serve as a downgrade substitute. However, its reduction in key performance may preclude a direct drop-in replacement for the original part in all applications. The two devices are fully aligned on memory density (9Mbit), organization (256K x 36), interface type (Parallel ZBT), voltage range (3.3V ±5%), and physical package (165-CABGA). This establishes the fundamental hardware compatibility. The primary technical divergence lies in access speed. The original device (71V65603S133BQG) features a 4.2 ns access time, supporting a clock frequency of 133 MHz. In contrast, the substitute (71V65703S85BQGI) has an 8.5 ns access time, resulting in a significantly lower maximum operating frequency—typically around ~117 MHz or less. This difference directly impacts overall system data throughput and reduces timing margin. If the original system operates at or near 133 MHz with stringent timing requirements, the substitute will fail to meet performance demands. Substitution is feasible if the system operates at a lower frequency with sufficient timing headroom, but a thorough re-validation of the system timing is mandatory.