I'd like to correct/amplify/underscore some things on the USB to serial cable.
John said:
3) Serial to USB cable, again Windows 10 can and will throw a major strop, UNLESS the driver file has a digital signature that it recognises.
Easiest solution is to look for a Vendor who sells one that is Windows 10 Certified, this will save hours of tedious head scratching!
One the main companies that make the USB to serial integrated circuit, used in your USB to serial cable (it's small) is Prolific. Seems a company in China made a cheaper clone of this chip. So later official Prolific drivers were designed to try to lock out the illegal clones. That did not stop a lot since many people had the old driver and used that.
So Prolific and Microsoft went one step further, and Microsoft now directly loads and provides the official Prolific driver, thus "locking out" the clone cables.
The whole upshot is you or your friends may certainly have a USB to serial cable that "Worked before" and now does not. It's not the fault of Windows, they are supporting a legitimate company from being subject to intellectual theft and loss of profit.
So if you "original cable" used to work and now it does not, just get a new one, the "legal" ones are more expensive, the $2 ones are clones and won't work on Windows 10.
Greg