I fact hard drives and similar rotating disc media are not random-access according to your otherwise reasonable definition. Modern (ie. anything that was ever

I fact hard drives and similar rotating disc media are not random-access according to your otherwise reasonable definition. Modern (ie. anything that was ever intended for personal computers and probably every harddrive ever sold by IBM as "DASD") hard drive does not known where given sector is physically located on the platter and does not care what is the current angular position of the heads. Instead it seeks to correct track and reads whatever data is there until it gets to sector header with correct sector address and then either reads or overwrites the sector (ie. it does have to touch irrelevant data).