A High Speed Digital Cassette Drive, which also has NMI capabilities, allowing you to dump the contents of the machine to tape.
The manufacturer mentions: "It used discarded Adam Colecos cassette units in a completely original circuit board, ROM and casing entirely designed, programmed and made in Uruguay. It was completely computer controlled and featured an NMI button to save games automatically, among other things. The designers later programmed
Buggy Ranger,
Freddy Hardest en Manhattan Sur (aka Guardian Angel),
Narco Police (Amstrad CPC, MSX, PC, ST, Amiga and Speccy versions) and
Megaphoenix (PC version)."
