Installing digitalwritefast Arduino Library

 The ZXPS libraries require the digitalwritefast library. To install it or confirm that you have it...
 Open the menu Tools > Manage Libraries and type in "digitalwritefast".
  If it isn't installed it will give you the option to install it.  Do so.
digitalwritefast
If it is not yet installed you will see something like above.
digitalwritefast installed
If it is already installed you will see something like above.