The Split & Combine plugin allows you to easily divide a large file into as many parts as you need, or into parts with a specified maximum size (e.g., for transfer on removable media - CD/DVD/floppies). Later, you can join all parts back into the original file and check the resulting file for transfer errors (using a CRC checksum). This can be done using this plugin or using a simple batch file (a special .bat file is prepared when splitting a file; you cannot test the CRC checksum using the batch file).
See the Menu Extension section in Using Plugins for a description of basic operations with the menu extension.