Specification for LC-81 Tape Drives
Storage for the LC-81 is based on tapes. These can be of any kind: paper tape, audio cassette, audio open reel magnetic tape, etc. It can also be "virtual tapes", that is simulated by non-tape media such as floppy disks or even a computer files managed by a Tape Simulation program.
In any case, there is a standard way for applications to communicate with tape drives. Such standard is specified in this document in full detail.
VTFS File System
VTFS stands for Virtual Tape File System. It is intended as an abstraction for programs running at the LC-81 minicomputer for interchanging data between disimiles tape-based storage mediums. Tapes can be either real such audio cassettes and open reel audio tapes, or virtual, simulated with Floppy Disks or ROM memory.