HP DC100
The DC100 tape format and drive was developed by Hewlett-Packard and introduced as a data storage mechanism for the HP-9825 programmable calculator. The DC100 tape cartridge was a scaled-down version of the DC300 cartridge pioneered by 3M, and represents an early version of what is now referred to as the QIC Mini Cartridge
This format was used in the HP series 80 calculator/computer systems of the late 1970s and early 1980s. It was also used in the HP 2640 series of computer terminals.
The DC150 cartridge, a variation with slightly higher capacity, was used in Digital Equipment Corporation's DECtape II drives.
The DC100 tape is based on the 1972 patent number U.S. Patent 3,692,255.
DC100:
Fast Access Cartridge Transport (FACT)
3M manufacturing secrets.
Base plate flatness.
Guide posts (essentially the 5 "axles" in the cartridge) into the base plate with sufficient perpendicularity.
Guide-post surface finish. Too rough, abraded the back of the tape. Too smooth, tape adheres to the guide through stiction, which causes speed flutter on the tape. The right surface treatment was found to be lapidary tumbler, a recipe of abrasive and burnishing compound.