2.3.1 μPROM Architecture and Address Space

Architecturally, the μPROM is structured into different memory arrays with 8-bit addressing. Each array is 256 x 9 bit words. The total number of memory array per device is die-dependent and can vary from 194 for the smallest die (MPFS025) to 553 for the largest die (MPFS460). The address bus (ADDR) is 16 bits wide. The lower 8 bits, ADDR [7:0], are used to address the individual 9-bit words while the upper 8 bits, ADDR[15:8], are used to address the individual memory array blocks inside the device.

The following figure shows a simplified block diagram of the μPROM memory.