Fixed my UEFI-only boot problem on an Intel NUC. Other modern computers might have the same issue ...
Environment:
I run TC mostly like a CD, and put my data on another device. That is, when I burn TinyCorePure64 to a usb stick with DD, or other burners, that means you end up with basically a "cd on a stick". Makes sense since the image when burned shows up as an iso9660 file format on your usb stick.
UEFI - it would never show up as a bootable device on my NUC. Always had to resort to 3rd party uefi burners. Not now ..
Secure Boot: ok, simple enough to turn that off.
UEFI: I run uefi only for speed reasons. The framebuffer is fast and gorgeous on a modern machine like the NUC that support the framebuffer well. No legacy or CSM is active. My offshore "mini-pc" - not so much.
BIOS / Setup fix: I found in my setup, that the system was not set to boot optical drives. I never intended to hang a real optical drive off it, so I ignored that setting being unchecked.
Then the light-bulb event: Since the stick is emulating a cd, using the iso9660 format, it IS an "optical drive" as far as the computer is concerned.
Once I did this in my setup:
Optical [X]
And rebooted, TADA - the usb stick shows up as bootable, boots up fine, and now Tinycore in all it's zippy framebuffer glory on the NUC. UEFI-only baby!
Interestingly enough, there is a similar setting in my "mini-pc" for that as well, but unfortunately, the framebuffer support is sluggish and sloooow. So xorg is going to be used on that cheap pc.
Anyway - just a hint for those trying to run TCpure64 as uefi only on a modern machine - and of course if you just dd'ed the iso to act like a cd-rom drive - see if your bios/setup has allowed for "optical" drives being allowed to boot!