The blog post uses conventions associated with the machine in question, the BBC Micro, which is an iconic 1980s UK machine. It was pretty much "Disc" back then, e.g. the dreaded "Disc error 0E" from the OS, or the spelling written on the discs themselves, e.g. this Watford Electronics Diagnostics disc:
http://www.computinghistory.org.uk/det/21293/Diagnostics-Dis...
Not sure if it's a UK thing or a 1980s thing.