ScanDisk showed up in DOS 6.2 back in 1993 and instantly became the go-to fix when your hard drive started acting sketchy. Before that, you had CHKDSK, but ScanDisk was faster, smarter, and could actually repair file allocation table (FAT) errors instead of just telling you something was wrong. It could scan for physical disk errors, mark bad sectors, and even recover data—huge if you were living on 486s and early Pentiums with drives under 500MB. Microsoft kept improving it through DOS 6.21 and 6.22, and if you remember watching those blue-and-yellow progress bars crawl across the screen, you know the mix of hope and panic it gave every time your PC didn’t boot right.