[lunatic]

The chip is physically the same in the SS10 and SS20. The PROM image from Sun (v2.25) is NOT the same, but different. However, there is a combined PROM image from Ross (v2.25R). It's the same image for the SS10 and SS20. Technically, you only need the 2.25R for the latest generation Colorado 4 HyperSPARCs (166MHz and up I think...). The older HyperSPARCs (150MHz and lower) will work with the 2.25 from Sun. Fun fact: fast HyperSPARCs will benefit from the slightly faster Mbus on the SS20 vs. SS10 (50 vs. 40MHz).