S1.1 | S1.2 | S1.3 | 64K Block
-----+-----+------+-------------
ON | ON | ON | 00000-0FFFF
OFF | ON | ON | 10000-1FFFF
ON | OFF | ON | 20000-2FFFF
OFF | OFF | ON | 30000-3FFFF
ON | ON | OFF | 40000-4FFFF
OFF | ON | OFF | 50000-5FFFF
ON | OFF | OFF | 60000-6FFFF
OFF | OFF | OFF | 70000-7FFFF