The SH7305 is equipped with a number of different built-in memory areas with various properties.

RS Memory #

• Size: 16376 bytes
• Address range: 0xFD800000 to 0xFD803FF8

Holds important OS values and code (including code that writes to the Flash), should not be modified carelessly.

IL Memory #

• Size: 4096 bytes
• Address range: 0xE5200000 to 0xE5200FFF

Appears to not be used by the OS.

X Memory #

• Size: 8192 bytes
• Address range: 0xE5007000 to 0xE5008FFF

Divided in two pages: page 0, from 0xE5007000 to 0xE5007FFF, and page 1, from 0xE5008000 to 0xE5008FFF.

Memory from 0xE5007000 to 0xE500701F has memory written to it then read back in the bootloader.

Y Memory #

• Size: 8192 bytes
• Address range: 0xE5017000 to 0xE5018FFF

Divided in two pages: page 0, from 0xE5017000 to 0xE5017FFF, and page 1, from 0xE5018000 to 0xE5018FFF.

Appears to not be used by the OS.