[wroteafaq]

Hi, folks.  I can't believe I'm new here; I've been slinging SGIs for a really long time, but have been away for a while and am now getting back in.

Quick question (I think):  I have a rather large pile of mixed Indigo parts that I want to turn into as many working systems as possible.  I have at least one working 3K system and one working 4K system, and probably more.  Since in many cases I don't know which CPU was in which box, I don't know which backplane has the correct E^2 settings for which CPU.  I have the necessary PROM burner here, but if there's an easier way I shouldn't have to press it into service.

So please tell me if I have this right:

1. Inserting a 3K CPU into a backplane with a blank/erased E^2 will cause the CPU to initialize the E^2.
2. Inserting a 4K CPU into a backplane that previously held a 3K will cause the CPU to "upgrade" the E^2.

But I don't know what happens if you plug a 3K into a backplane that previously ran a 4K.

Nor do I know what happens if you plug a 4K into a backplane with a blank/erased E^2.

I can certainly confirm/determine all this experimentally, but I'm a little oversubscribed at the moment (including having many trees to cut up as a result of a serious windstorm a couple of weeks ago), so it would be of tremendous help if anyone could sort me out.

Thanks much.

Jonathan