1970-75; originally an IBM code name; the designation for a device containing two such disks was 3030 (each disk containing 30 megabytes), the same as the model number of a well-known Winchester rifle
British Dictionary definitions for Winchester disk
Winchester disk
noun
1.
a type of hard disk in which disks are permanently sealed, together with read-write heads, in an airtight container to keep dust out
Word Origin
C20: named after the 3030 Winchester rifle, as the original device would have had 3030 as its IBM number