What’s diff between “TR2” with “TR2A” ? I have checked on sony support site, but there’s no “TR2” without a letter at the end, such “A” or “AP”.
Thanks,
Dhend

There is no actual TR2 model. It’s merely a designation of the iteration of the TR series. Thus TR2 is the TR in its 2nd release. 

The P at the end of any Sony notebooks usually means it’s shipping with Windows XP Professional instead of Windows XP Home Edition.

Before, I have same perseption with you.
I have a TR2A, yesterday my friend sent his TR to me for re-install with
xp-pro. I Checked the part number on the unit is “PCG-TR2” without any Letter “A” (XPHE) or AP (XPPro) or “B” (Japanesse version).
I asked him where’s he bought the unit, he got from used computer shop.
Is it refurbished unit or not ?

Where exactly does it show this? On the physical body? The underside? It’s possible that it may be from another region or perhaps it is refurbished. At any rate, it’s second generation so it’s probably not a big deal.

What happened to the 4th series? It went from the TR3 series to the TR5 series…..

4 is considered an unlucky number in asian cultures because it sounds like the word death. Maybe that’s why it was skipped.