As follow up to the entry about initial setting of Yamaha RTX on Mac, here is how to run tftp on Mac and do a firmware update:

First, start tftp server:
sudo launchctl load -w /System/Library/LaunchDaemons/tftp.plist

Then run these commands
tftp xxx.xxx.xxx.xxx (the IP address the router)
tftp> mode binary

tftp> put rtx1100.bin exec

Then stop tftp

sudo launchctl unload -w /System/Library/LaunchDaemons/tftp.plist