Norton Utilities 4.00 for DOS, released in 1987, was the go-to toolkit for anyone trying to squeeze performance and reliability out of their PC in the pre-Windows era. This was the version that really solidified Norton’s rep, packing tools like Speed Disk to defrag your hard drive, Disk Doctor to catch and fix errors, and UnErase to save you when you nuked a file by mistake. Compared to earlier 1.x and 2.x releases, 4.00 was faster, more stable, and supported larger drives that were starting to pop up in late-’80s PCs. If you were running DOS back then, Norton Utilities wasn’t optional—it was the secret weapon that kept your system alive.