Torvalds at LinuxCon: The Highlights and the Lowlights

“For the first two or three releases you not only had to have an AT hard disk,” he continued, “you had to have the same AT hard disk as I had because the geometry of the hard disk was hard coded in the source code. You could have a different AT hard disk, but you had to change the numbers to match how many sectors you had. So, the first releases were a bit unpolished.”