laser servo (LS)
With the LS-120 diskette, also known as a super diskette, the magnetic storage density is significantly increased by previously applied servo tracks. The closely spaced guide tracks, which are applied by laser, allow very precise guidance of the read/write head. Compaq's LS-120 diskette has the same format as the familiar 3.5" diskette, but with a storage density of 2,490 tpi, it offers a storage capacity of 120 MB. The access time is just over 70 ms, and the data transfer rate is 560 KB/s.