The feature only existed in the A2000, A3000 and A4000 because of the forethought of Jay Miner and team when building the original Amiga 1000. Many computers o

The feature only existed in the A2000, A3000 and A4000 because of the forethought of Jay Miner and team when building the original Amiga 1000. Many computers of the time could have been modified to use an externally sourced video clock (basically anything that used NTSC / PAL video), but Only Amiga Makes It Possible (tm) by including the signals on the DB23 video port of the A1000 and subsequent models at virtually no cost. Even the CGA card of an IBM PC could have been modified in this way. I can imagine a hack where the flash attribute in text mode gets used to act as the overlay key, but it would have been pretty darned ugly. Of course the very thing made genlock work so well on the Amiga (the use of bitplanes) was a factor in the ultimate demise of the Amiga in the 1990s. It's funny how the memory bandwidth tradeoff changes things.