Did you like, read the pages you googled?
http://www.fileinfo.net/extension/cal
Program(s) to open a cal file Mac / Windows: Broderbund Print Shop, Printmaster, Calendar Creator; American Greetings Create-a-Card
Program(s) to open a cal file Mac: Adobe Photoshop
Windows: Adobe Photoshop; Corel Paint Shop Pro; Graphics Converter Pro