This might be inaccurate so if you know better please comment and I'll correct this.
List of interesting OFW versions
- 0.20 - Very first firmware confirmed to exist. Can only run on CEB prototypes (probably unobtainable at this point).
- 0.85 - First version for DECR devkits. This is the earliest firmware version that can be installed on somewhat obtainable hardware.
- 0.90 - First version that has a PUP installer (all previous versions only had eboot.rom).
- 0.95 - First version for DEX devkits.
- 1.00 - First...
List of interesting OFW versions