Shrinking the drive
On the left is the RA80 disk drive from DEC. It was among the popular 14-in platter disk drive technologies of the 1970s. The RA80 disk platter had 1,092 tracks with 31 sectors, each capable of storing 412 bytes of data.
On the right is an 8GB Microdrive from Seagate. Microdrives, launched in 1999 by IBM, came in 1.8-in, 1-in and .85-in sizes and were popular for use in MP3 players, such as iPods. Discontinued in 2009 as NAND flash storage took over in mobile devices, microdrives are a good example of how the harddrive industry been able to shrink the areal densities.
Today, a 2.5-in 2TB laptop hard drive sports an areal density of 760Gbits per square inch.