Hard Drives are items that can be found in Crash Sites found around the world. These can then be used to unlock alternate recipes. With these steps, you won't even need the Object Scanner to find them. Once you research the Hard Drives in the MAM you can choose two different blueprints and continue rolling the selections until you have found an alternate recipe that you want.
Hard Drives can be found all over the map at the different crash sites. Once you find one, you'll see a container like this that you can open for different resources as well as your sought after hard drive.
The Satisfactory Calculator offers a map with all locations of crash sites with Hard Drives around the map pictured below.
Make sure to come prepared to these crash sites with weapons. Many crash sites are surrounded with creatures ready to protect their precious Hard Drives.
Once you get a Hard Drive, you can take it to the MAM or Molecular Analysis Machine and scan them. Once the scanning has complete, you can choose whether you want to accept one of the recipes presented to your, or, rescan the drive to reroll what recipes you get.
That's all you need to know about Hard Drives. So get out there and start collecting them, in the end the alternate recipes can make your life much easier in the long run since you'll have potentially easier ways to produce certain resources.