@rednova
As you can see, the amiga community is alive and well. ;-)
Not sure if your original questions were actually answered, so here is a quick summary:
The AmigaOne is a computer platform based on the Teron series of PowerPC POP mainboards, mainly intended to run AmigaOS version 4.0 created by Hyperion Entertainment in Belgium.
The AmigaOne hardware is similar in concept to a regular pc of the same vintage, except that the AmigaOne has a PowerPC CPU and a different Northbridge chip.
AmigaOne SE had the CPU chip soldered on the motherboard, plus an AGP slot and PCI slots.
AmigaOne XE had the CPU chip on a daughterboard, plus an AGP slot and PCI slots.
MicroA1-C had the CPU chip on a daughterboard, plus onboard graphics chip and one PCI slot.
None of these boards are produced anymore. Some other boards were planned but not released.
AmigaOS4 is an actual PowerPC operating system. It has built-in ability to provide emulation for programs and sequences of code which were written in 68xxx code.
For the AmigaOne, this allows for compatibiliy with older programs which are "system friendly", which do not depend on the old Commodore Amiga hardware, or features present in older versions of AmigaOS. There are many really old programs which are not compatible with AmigaOne. The AmigaOS4 version of E-UAE creates the right environment for these programs.
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redfox