The SST-6809 has 512KB of static RAM.

The lowest 64KB provides the processor's workspace RAM.

There is a Memory Latch Select that allows mapping 32KB banks from the remaining 456KB of static RAM into the lower 32KB address range of the processor workspace ($0000-$7FFF)

The remaining RAM address range $8000-DFFF remains in place allowing a stable place for interrupt service handlers, stacks, bank mapping code and more.

ASSIST09 reserves D000-D100, F000-F3FF for its expansion ROM, and F400-FFFF for itself.

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