Nothing is easy to imagine and very bad to experience than losing a latest update of your project. As we speak of assembler projects the slightest modification in a source file can have a large impact on the further development of even the smallest example. A bit exaggerated? Let's hope. Worse is to notice when an entire project is deleted from disk (which can have many reasons) and you can't recover it.
As for all projects in any programming language a Version Control System is a nice invention. For this some guys have developed Git, it's free, open source (for those who like to vie the source and perhaps contribute) and on Linux Mint (and other Ubuntu like *nix-es) easy to install.
sudo apt-get install git
Type in your root password if necessary and voila, you're done. I'm not going to discuss the many commands to use git from the command line, that's up to you. Not that I don't like command line instructions but a nicer option is available.
Let me be honest. I like programming and experimenting and testing even if it's in a terminal. I'm not too lazy to read the --help of some commands but when it comes to git....... I prefer a more easy way to take care of the versions of my programs.
Because programming in assembly language is very terminal based ( unless you use QtCreator ). I prefer a version control system client in a window. Not easy to find a good one, true, at least I didn't found one from the first moment. After a while I've found one namely SmartGit. To install, download the .deb package (there are other ways to install it too but you have to look on their website), install it with the package manager and again voila, you ready to go. Be sure to select the non-commercial use unless you want to buy it which isn't a bad option after all.