UK Vs. US
By the 20th century, the k-spelling was more popular in America, while the c-spelling was preferred in the UK. In the 1950s, when the American company IBM pioneered the first hard disk drive storage devices, the k-spelling was used. Consequently, in Computer terminology today it is common for the k-spelling to refer mainly to magnetic storage devices (particularly in British English, where the term disk is sometimes regarded as a contraction of diskette, a much later word and actually a diminutive of disk).
Read more about this topic: Spelling Of Disc