Power Mac G4 DP 1.25 Ghz FW800
For PowerMacs -- FW800 signals OS 9 bootability death.
Every other desktop/portable loses OS 9 bootability with DDR.
No way around it, and if there was -- portions of the machine will fail to work, due to lack of ROM extensions/patches for hardware on the motherboard.
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We used to have companies willing to patch the ROM to allow people to get around some of Apple's hurdles, but no one really has come forward since the death of the clones.