well, S3C2442 and S3C2442B, just for an example, meet all those criteria: they have same footprint, same family, same pinout, same supply voltage. I leave it as an exercise to readers, why they are not compatible nevertheless, though there hasn't been any hackish involved from EE side.

When you found out, you might start to ponder if same problems might apply to swapping 3430 with a 3630

/j

your single freaky exception to the rule doesnt disprove the point that it may actually work.

what is the problem between thos two chips you mentioned?

differing electrical specs for some pins, here pullup vs pulldown on some GPIO

Reading through this entire thread, I almost regret ever seriously suggesting in other threads that hardware mods to the N900's SoC might be feasible if someone was dedicated enough to destroy a bunch of N900s in the attempt.

As much as i keep looking i cannot find anything different apart from the speed so i suggest more work be done on this, i really cannot see a problem here because they are same family same package same pin outs/in.

There are many references to these 2 and i suggest you start with the wiki page....

http://en.wikipedia.org/wiki/Texas_Instruments_OMAP

take it from there.

NB OMAP3

The OMAP3 [1] is broken into 3 distinct groups: the OMAP34x, the OMAP35x, and the OMAP36x. OMAP34x and OMAP36x are distributed directly to large handset (such as cell phone) manufacturers. OMAP35x is a variant of OMAP34x intended for catalog distribution channels. The OMAP36x is a 45nm version of the 65nm OMAP34x with higher clock speed.[2]

http://www.linuxfordevices.com/c/a/N...shrinks-OMAP3/

Finally, TI confirms that the OMAP36xx SoCs are software-compatible with previous OMAP2 and OMAP3 processors, which run operating systems including Windows Mobile, Linux, Android, and Symbian.

No, they are not the "same family". A 45nm reduction very probably means that all the input pin levels have changed (they could also not have changed, but I'd doubt it, considering we're on the embedded world).

I see two problems with your master plan:
A) Different processor families. Any single discrepance probably means your mod ends up as a frankenstein.
B) I disagree that soldering the processor is an "easy" task. For a start, try replacing the N900 processor with an identical processor. If you manage to unsolder it without breaking it, there's a job waiting for you at an assembly line, as said. Your über-human abilities will replace a quite expensive robot there.

Ah, don't break the memory either while you're at it. It's on top.

On a further note IF this is possible giving the fact you have the replacement cpu then once proven would in fact bring the N900 into spec with the more advanced hardare Meego requires, also the software already exsists on this forum for overclocking the old cpu.

I will hazard a guess and set the N900 to the lowest voltage for overclocking before firing up after a refit.

It's already been explained to you what's different: Basically, just because the pins are in the same place and are designated as the same thing DOES NOT mean that they are compatible. Simply put, just because the same pin name is used for the same pin in the same spot on two different generations of chips, doesn't mean they actually do the same thing, and if they do, it doesn't mean they do it the same way.

Meaning, 34x chips might expect current into pin xyz to come at x volts, at the rate of y mhz, etc (I'm pulling the numbers and units out of my *** here). 36x chips might have the same pin xyz, but be built to have current come in at a volts, at b mhz, etc. Different electrical currents/signals, even if the actual pin designation/purpose is the same. SO when you stick a 36x into a 34x slot, the same pins might work completely, but most likely, some will be fed too much / too little power, or get signals at the wrong rate, and thus the entire thing doesn't work, or works in an unstable / half-assed way.

Your wrong you know because they ARE same family and because is so small is so easy to lift.

Have you any idea just how easy it is to replace these components? have you ever tackled this kind of work? i know you have not simply by your comments.

"Easy to lift" is completely irrelevant in every context, not that it's actually "easy to lift."

And I know you have not either. I've heard horror stories on removing chips like this, especially ones from Nokia that come underfilled and in PoP format, from people who do that sort of thing regularly as part of their job. Costly reworks of boards after pulling off the chips, destroying multiple devices trying to get one that can even be reworked.