U specifies that the constant is unsigned, while L specifies that the constant is long. The code will be shorter and quicker. 2.0 Change your int variables to long if they have to be bigger than 255. If they should only contain values between 0 and 255, use an unsigned int . If your application uses the delay function, you'll have to adapt your delay values.
Several functions have new names.
You will probably have to change the name of the header files that you include. Results are always returned into the DE register. Assembly identifier are exported using the .globl directive. Multiple RAM banks are only supported by MBC 1. With multiple ROM banks, addresses 0x0000 to 0x3FFF are reserved for the fixed ROM bank, while addresses 0x4000 to 0x7FFF are switchable, i.e. can be used for any bank.