Turbo Freezer 2011 CartEmu Configuration Registers:

D590: bank select (bit 6..0)
Sets (8k) base bank, 0-127 if accessing flash ROM, 0-47 if accessing RAM
Writing this register also enables CartEmu (sets D591 to 1)

D591: cart enable (bit 0)
0 disables the CartEmu, 1 enbles it

D592: RAM ($8000) bank select (bit 5..0)
In 8k+RAM mode sets the optional RAM bank at $8000-$9FFF). Allowed values: 0-47
Writing this register also enables RAM (sets D593 to 1)

D593: RAM ($8000) enable (bit 0)
In 8k+RAM mode setting this register to 1 enables RAM window
at $8000-$9FFF. Setting this register to 0 disables the RAM window.
In other modes this register doesn't have any effect.

D594: CartEmu mode select (bit 2..0)
Sets the cartridge type:
0 = cartemu off
1 = 8k
2 = 8k with optional RAM at $8000-$9FFF
3 = 8k old (Turbo Freezer 2005 banking, using D540-D57F and D580/1/4/5)
4 = 16k
5 = OSS
6 = AtariMax (bank select = D500-D57F, D580-D58F=off)
7 = CartEmu Menu (internal use only)

D595: CartEmu config (bit 2..0)
bit 2: 0=keep settings on reset, 1=activate CartEmu menu on reset
bit 1: 0=CartEmu uses Flash, 1=CartEmu uses RAM
bit 0: 0=flash/RAM write protect, 1=write enable

D596: SDX Configuration (bit 1..0)
Controls ultimate 1MB SDX emulation
0 = SDX off
1 = SDX read from RAM (bank 0..47)
2 = SDX read from ROM1 (bank 0..63)
3 = SDX read from ROM2 (bank 64..119)

