You just poured a ton of time into your Heccintosh 2900 and got most things running like butter; "Time to back this up" you think as you reach for your USB 3 external hard drive... The USB cable seats snugly in the port as the your eyes watch the desktop... but... nothing shows up.
"Where is my drive??"
It turns out, you've been hit by a common problem - macOS is limiting the number of USB ports you can use!
There are two major parts to this:
An extensive background on what the issue is, why it happens, what our options are, how to accomplish those fixes, and how many apples you can fit in a bag.
A walkthrough for using the mostly-automated USBMap.command for setting up an SSDT that controls which ports you will use.
If you've gone through this all before and just want to use the script - skip ahead to the USBMap Script section.
For everyone else - just continue onto the next section and we'll dive right into some terms!