Pd Gem fixes for Mac OSX v11 (Big Sur) or 12 (Monterey):

1. Open the Gem folder in your user "Documents/Pd/externals"
2. In a text editor Edit gemdefaultwindow.pd to change "gemmacoswindow" to 
   either "gemglutwindow" or "gemglfw3window" 
3. restart Pd



for new Macs with the M1 chip:

At command line (terminal):
softwareupdate --install-rosetta   