ATmega128 is one of the AVR microcontroller. Large memory (128KBytes) can be used to make a big project. For example, if you create a storage system using the MMC and use BASCOM AVR as the programming language, then you have to load a very large libraries into the memory of the microcontroller. And this can not be done if you are using a microcontroller with a small memory such as ATMega16 or ATMega8535. Therefore, you can try using AVR ATmega128 to complete your major project.
However, you would have difficulty in assembling and soldering components on this ATmega128 microcontroller. This is because ATmega128 an SMD component. And you must be able to make a double layer PCB if you want to use a ATmega128 microcontrollers and use part of DIP components (such as IC MAX232 or another). If you want to combine the two types of these components, then I have tips for you. Make two single PCB layer and combine with pin headers. The first is an adapter PCB for ATmega128 microcontroller and the second is used for the other DIP components. And then combine it with pin header (male and female pin header). You can see PCB adapter for ATmega128 microcontroller in the picture.
DIY – Do It Yourself project
Hopefully this tutorial ( AVR ATMega128 Schematic Circuit Adapter DIY ) can help you in completing the project.