Q Does Yosemite support my Epson and Oki printers?
Generally speaking the best initial approach is to connect the printer, power it up and let it initialise, etc., then open the Printers & Scanners pane in System Preferences. With the Print tab selected, click on the + icon at the foot of the list on the left, and look for the printer there. If Yosemite has support directly available, that should enable all the printer’s features.
Even if your printer model is not listed on any site, it may still be possible to get it to work. Some printers have emulation modes, in which they function as if they were a generic model, and you may find putting the printer into that mode allows OS X to support it. Many older printers are supported by free Gutenprint, which is known to work with OS X 10.2 to 10.8, and may work with later versions too.
Printing in OS X uses an open source system known as CUPS, which you can also access directly if you need to tinker. You can do this by pointing your browser at the CUPS page, although newer versions of OS X require that you first enable the web interface to CUPS by entering
at the command line in Terminal. CUPS is documented here.