Star Bonifacio Echeverria, S.A. based its post-World War 2 submachine design on the German wartime MP40 which was marketed as the Star Z-45. This was followed by an evolution of the line that included the modernized Z-70 used by Spanish military elements. By 1984, it was determined to produce a new submachine gun based on an all-new lightweight, compact design which became the Star Z-84. The Z-84 showcased an Israeli UZI-esque appearance and proved itself reliable even after being submerged. However, the American civilian firearms market was closed off to Star following the 1994 Assault Weapons Ban which heavily curtailed possible sales in the US. Though the weapon was trialled by a several nations in the interim, it was never adopted. The Star concern then went defunct in 1997 after a 92-year run of firearms development and production.
The Z-84 was chambered for the widely-accepted 9x19mm Parabellum German pistol cartridge and fired through a blowback system of operation utilizing an open bolt design. Rate-of-fire was 600 rounds-per-minute with feeding from a 25- or 30-round straight, detachable box magazine. As in the Israeli UZI - a configuration copied globally - the Z-84's magazine was inserted into the base of the pistol grip. The action allowed only for full-automatic fire which meant that the operator had to take special care not to clear the magazine too quickly. The grip sat at the centerpoint of the design which, when loaded with a magazine, led to a well-balanced, inherently accurate weapon. The trigger loop was purposely large for use by a gloved hand and protected sight assemblies were fixed at the front and rear surfaces of the receiver in the usual way. A short barrel was largely concealed by the receiver. An optional twin-strut folding stock was available which, when extended, gave the weapon a running length of 24 inches. Length was reduced to 16 inches when the stock was folded over the receiver by way of a hinged. Weight was a handy 7lbs while overall construction incorporated stamped steel and specialized castings.