It's not just the source code, it's also the tools to edit/build it, the directory structure, the operating environment (OS, network shares, servers) and more.

It's not just the source code, it's also the tools to edit/build it, the directory structure, the operating environment (OS, network shares, servers) and more. Example: You can still buy a copy of Visual Basic 6 on eBay. Does your laptop even have an optical drive to install it? Do you have the patches that were released for it?