F446RE has 4GByte address space...
But its RAM is 128KB and Flash is 512KB...
Most of the memory section is reserved...
What are the purpose of these reserved memories?
It's not "reserved memory", it's "reserved address space."as in "this part here is where we could add more om-chip flash, and here is where we could add more on-chip ram, and this piece is where we could add off-chip memory, and here is room for more peripherals..."The ARM v7m (cortex-M3, and M4) actually defines the address space, dividing up the 4G address space into 8 separate functions with 0.5GB allocated to each one. (Code, SRAM, Peripheral, write-back cacheable RAM, write-through casheable RAM, Shared Device Space, Non-shared Device Space, and System.)
https://developer.arm.com/documentation/ddi0403/d/System-Level-Architecture/System-Address-Map/The-system-address-map