The A16 pin on the PORTG/AUX connector is connected to A16 (address pin 16) on the SRAM. ATmega103(L) and ATmega128(L) support up to 60 KB of external SRAM. The STK501 SRAM footprint is for a 128 KB SRAM. Implementing software control of the A16 line will increase the memory range from 64 KB to 128 KB. This line is pulled low by default, addressing the lower 64 KB of the SRAM.
Figure 1. SRAM Block Schematic
