The Apple Workgroup Server 9150 is the only Apple Workgroup Server

Apple Workgroup Server

Apple Workgroup Server and, later, Macintosh Server, were the names given to selected models of Macintosh computers which were sold by Apple Computer with additional server software and sometimes bigger hard drives. Apart from that, they were mostly identical to computers out of Apple's...

 model not based on a desktop Mac. It featured an 80 MHz (speed bumped to 120 MHz in April 1995) PowerPC 601 board in a Quadra 950 style case . The internal bay of the 950 case was filled with a tape backup drive. It has 8MB of RAM (expandable to 264MB). It runs System 7.5 to Mac OS 9.1.