Before I was achieving a similar result by showing different images based on how you chose to boot. But that wasted a lot of space.
So UB2 has dropped in size as a result, from ~260K to ~176K. No menu or anything exists yet, so it will go up. But much better. Assuming there aren't big problems discovered tomorrow, the hard part is done now.
More very interesting discoveries to come relating to SD boot, once I fully comprehend the significance of what I've learned/am realizing... better to wait till I'm awake though and can think about it more.... it's late and I could be totally wrong.
Anyway, implemented now in 2ndbootloader (UB2):
* safety stuff; do-the-right-thing behaviors
* 512 buffer size default for boot partitions
* new boot modes
* New keypresses for recovery boot vs. normal boot on SD/emmc
* text now works
* instant feedback on what is loading...
* smaller size
* misc fixes
Another good day I think. Especially, and I emphasize-- I have no NT