Just mentioning that "unlimited undo/redo" meant that it was really fast to undo and redo one step in Word. This system didn't necessarily enable an undo histo

Just mentioning that "unlimited undo/redo" meant that it was really fast to undo and redo one step in Word. This system didn't necessarily enable an undo history like we expect from word processors now. In fact, up to Word 5.1a for the Mac and Word for Windows 2.0, Word didn't have undo history. Undo would undo the last action, and then it would undo the undo. I believe undo history was added to Word 6.0.