Please help Identify Italian frame
BMZ presumably stands for Biemmezeta, an Italian manufacturer from near Milan who did a lot of contract manufacturing for a lot of places (e.g. Performance Cycles) as well as sold bicycles under their own brand. More details on your location may help narrow down the bike's pedigree. 

As Daniel R Hicks estimates the date of the bike in the comments, it should be noted that BMZ was popular in the 1980s.