A “raw” ATmega328 from the factory is configured to run from its internal clock, and does not require an external crystal. Our ATmegaXX8 mini dev kits come with a raw chip, unless specially ordered otherwise.
However, once it is programmed with a bootloader that expects an external crystal (or technically, once its “fuse” bytes are set to require one– which happens as part of that programming process), it does require a crystal.
If you do not have a crystal on your target board, and you tried to program a bootloader, it’s possible that you may have *succeeded* once, which will make it so that it cannot be reprogrammed, at least until you add the crystal and caps.
