Originally Posted by LuMan
@Lonewolf10 - There is a +2A revision, but it's just a name really. I think it's something to do with the production moving to Amstrad. It was also black, as opposed to the previous +2 grey. There's also a +2B which just means the production moved from Hong Kong to Taiwan (I think...
No collection is complete without the +2A and +2B.
Amstrad took over production of the 128k spectrum and fixed a great many bugs in the ROM, which was then released as the 128k +2. After that, they went after the god-awful hardware flaws in the 128k design, and fixed those - and released the result as the +2A and the +3. (Said fixes sadly render quite a few games unplayable on the +2A/+3, but they had to be done).
The +2A is a +3 with tape drive instead of floppy. If you attach a floppy to the +2A, it will behave identically to the +3. The +2B was a further refinement to the +2A.
So in short, although the +2 is the most compatible
of the 128k spectrums, the +2B is the most mature and technically advanced design, whilst still retaining the internal tape deck. It's the only model that can utilise IDE hard disks via a cheap ROM/IDE-interface internal upgrade. All others require a nasty expansion port adapter.