Retrogamer asked me to tell something about emulating the C16, commodores failed semi follow up (better basic, less mem) to the C64

I think there are three ways.

1. you can download macmess (at macmess.org called messmenu)
you have to download a c16 bios, and leave that as a zipfile in the rom directory of mac mess (just like mame)
e.g. here: http://www.planetemu.net/index.php?section=roms&dat=638&action=showrom&id=846225

d64 files work*, do select the box with load floppydisk, (i've got an older version which actually is easier which is called mess.carbon.
*the file format is d64, the c16 shares the diskstructure with the c64

2. there has recently been a build of a windows c16emu remade for intel macs, see here http://sourceforge.net/project/showfiles.php?group_id=192837&package_id=244400

3. you can play lots of c16 games online here: http://plus4.emucamp.com/playonline.htm