Vince - no need for all that.
I guess I wasn't making myself clear, and I've seen many threads elsewhere that derail like this thinking it's a UEFI issue, whereas it is a security-issue on some modern machines *that just happen to be uefi-only*, where the ability to boot from a cd/dvd is locked out unless you take steps to open it up.
Yes, this is avoided by simply following Juanito's excellent instructions for creating a dual-boot mbr/uefi stick where the stick does NOT look like a bootable cd.
BUT, if one just does a "dd" or burn of an iso to a usb stick, on *some* modern machines that just happen to be uefi-only, they have the ability to disable booting from what they see as an optical drive - whether it is a real spinning disk, or a usb stick that has been formatted as bootable with the iso9660 as a partition on it.
That's why I wanted to point this out to any lurkers - if you do just a simple dd, or use Etcher or any other burner to the TinyCorePure64 iso, what you have is a bootable cd emulation as far as the computer is concerned. And if your computer has the ability to boot from an optical drive not set, it won't boot due to security settings in the bios/setup, NOT because of UEFI.
In essence all you have to do is one of two things:
1) Create a dual-boot stick following Juanito's instructions.
or - if you want to operate from an iso like just a live read-only cd:
2) Go into your computer bios/setup, and enable the ability to boot from an optical drive, *IF* you are simply going to burn an iso image, which has an iso9660 as the major partition to operate from. My Intel NUC actually *evaluates* the drive before allowing it to boot, and if it sees iso9660 - it won't - Unless I tell the setup that it is OK to boot optical, which the burned usb iso looks like to it with no spinning plastic.
So despite all this, it is NOT a UEFI issue. Just some modern rigs won't boot iso's from usb unless you let them. If you can't, or just don't want to do that, another solution is just as simple:
Follow Juanito's instructions. I've done it both ways.