Nintendo DMG-01 - Game Boy Console Manual page 15

TM
Game Boy CPU Manual
RAM which is in the controller itself. It still
requires an external battery to save data during
power-off though.
The least significant bit of the upper address
byte must be zero to enable/disable cart RAM. For
example the following addresses can be used to
enable/disable cart RAM:
0000-00FF, 0200-02FF, 0400-04FF, ..., 1E00-1EFF.
enable/disable is 0000-00FF. The suggested address
range to use for MBC2 ram
The least significant bit of the upper address
byte must be one to select a ROM bank. For example
the following addresses can be used to select a ROM
bank: 2100-21FF, 2300-23FF, 2500-25FF, ..., 3F00-
3FFF. The suggested address range to use for MBC2
rom bank selection is 2100-21FF.
MBC3 (Memory Bank Controller 3):
•
This controller is similar to MBC1 except it
accesses all 16mbits of ROM without requiring any
writes to the 4000-5FFF area.
Writing a value (XBBBBBBB - X = Don't care, B =
bank select bits) into 2000-3FFF area will select
an appropriate ROM bank at 4000-7FFF.
Also, this MBC has a built-in battery-backed Real
Time Clock (RTC) not found in any other MBC. Some
MBC3 carts do not support it (WarioLand II non
color version) but some do (Harvest Moon/Japanese
version.)
MBC5 (Memory Bank Controller 5):
•
This controller is the first MBC that is guaranteed
to run in GameBoy Color double-speed mode but it
appears the other MBC's run fine in GBC double
speed mode as well.
by DP
2.6. Cartridge Types
Page 15