I am awaiting delivery of a 250MHz CPU, and expect a reasonably plug-and-play upgrade - from techpubs, the process seems to be: remove lid & CD tray, undo screws, lift old CPU, drop in new CPU, tighten screws, reassemble and off you go.
Aside from larger cache and more MHz, it seems to be a like for like swap, and I have found no sign that this CPU is not suitable for teal I2s. However, the manual predates 250MHz CPUs, so I thought I had better check that there are no known niggles around this upgrade.
In particular, is a newer PROM likely to be needed? not sure what PROM version I have, but looking at some hinv posts, 200MHz CPUs seem to be revision 6.0 (SC 1MB or 2MB), same as a 250MHz, so I hope the answer here is no.
Hoping not to have a horror story to report!
Fuel; Indigo2; RiscPC Kinetic-StrongARM/448MB/RISCOS4.39 or Debian-etch; EspressoPC ViaC3/900MHz/256MB/Debian-testing; RPi B RISCOS5.21 or Raspbian-jessie; A5000/33MHz/FPA11/8MB/RISCOS3.11; A540/25MHz/FPA10/16MB/RISCOS3.11 or RISCiX1.21; R140/35MHz/4MB/RISCOS3.11 or RISCiX1.21