Creator of "Hot Hits" radio format Mike Joseph DEAD @ 90

Well known radio programmer including successful runs at legendary stations such as WFIL, WABC and many more.  Once he ventured out on his own and started his radio consultancy he launched the Hot Hit's format which was famous for only playing the current hit singles.  It is the ancestor of today's CHR or Top 40 format.  

Wikipedia has "Hot Hits" dissected if you want to learn more.   

Here's what Hot Hits WBBM-FM Chicago sounded like.