EZ-B prototype bullpup assault carbine
Apparently, this prototype was developed in Czechoslovakia in the 1970s, under the "Experimentální Zbraň" ("Experimental Weaponry") program. The engineer MIROSLAV FISER, from one of the many (then) State-owned weaponries research institutes, took the (then) standard Czechoslovakian assault rifle, the PUSKA Vz-58 (also known as the "Cz-58 assault rifle" or "Sa-58") as a basis for this weapon, converting to Bull-Pup the working system for it. The weapon was submitted to the "EZ" programme in the year 1975, as the second entry, thus becoming the EZ-B. The weapon shares some borrow-ups from the early British EM-1 and EM-2 British-made experimental bull-pup rifles of the 1950s as far as it's concerned for its external construction.
Photos and information from: Pierangelo Tendas