...Supports programming vis ISP, Serial (Optiboot - all parts with >4k flash, and all parts with 4k flash for which an 8k version is available) or VUSB (Micronucleus - where appropriate) There are 272 different versions of micronucleus built (and part of the 2.0.0-dev branch now), and optiboot will dwarf that number! 0 of those have been tested. Obviously, we are leaning very heavily on automation of configuration generation for this release. Half of the tinyNeoPixel speeds have had the assembly routines modified in major ways (there's no more stupid menu for the port), but they are untested. Virtual boot relies on rewriting the vector table, such that the RESET vector points to the bootloader.