ADSP-21479 and SDRAM MT48LC8M16A2

Hi All,

I'm trying to interface a MT48LC8M16A2 (128Mbit) part to an ADSP-21479 which is different to the part found on the EZ kit. 

I have made the required changes to the SDCTL (SDRAW12 and SDCAW9) and reflected them in a custom register resets file. 

I'm having trouble in understanding the linker SDRAM map for the EZ kit in order to translate them to the MT48LC8M16A2  part. 

Specifically, the address map found the EZ kit for MT48LC16M16A2 part is as follows.

seg_ext_swco { TYPE(SW RAM) START(0x00600000) END(0x0065FFFF) WIDTH(16) }
seg_ext_nwco { TYPE(PM RAM) START(0x00220000) END(0x0043FFFF) WIDTH(16) }
seg_ext_dmda { TYPE(DM RAM) START(0x00660000) END(0x009FFFFF) WIDTH(16) }
seg_ext_pmda { TYPE(DM RAM) START(0x00A00000) END(0x00AFFFFF) WIDTH(16) }

I'm interested in understanding where the holes in memory come from (0x440000 - 0x5ffffff )? Also why does the seg_ext_nwco section start at 0x220000 instead of 0x200000? Does this map ever need to change for my case?

I understand that this is a newbie question and it also accurately describes my knowledge in SDRAM.