I just bought a 'real deal' PSR640 . . .
Well, it SOUINDS great, anyway . . .
I am taking it BACK to the shop ASAP and buying either a cheapo PSR550 or a PSR1000/2000 series (I will mortgage my house if I do that)
Anybody had any experience yet with the 'flash ROM' method of storage of settings and registrations? . . . I assume that the flash ROM has a small lithium battery like a computer's CMOS battery to retain settings?

It is difficult to get info from Yamaha (although one of the tech guys there has been trying to help me with my questions)

Also, anybody had my experience (with my old PSR410) of having to play into a MONO channel PA . . . with a STEREO keyboard?

I notice that the voices cannot be panned in the middle, or they won't sound at all!

Anyway, I am probably going to take the quantum leap to the PSR1000 from my old PSR410 . . . and take the poor old PAR640 back, as I say . . . the only way to keep custom settings is to save and load from FLOPPY! The 'SuperCap' capacitor is SUPPOSED to retain settings for about a week . . . my settings were GONE in 2 days . . . go figure!

The PSR640/740 was originally designed to have 2xD cells in a holder in the base (the concave area is open on these units with no battery holder, but it is obvious that that is what was originally intended for the 'hole' . . . why on earth didn't they provide some sort of battery backup . . .

The PSR640/740 series are beautiful-looking AND great sounding units, and except for the non-battery issue, I love them!

But, unless I buy the cheap-looking PSR550, I have to notch up to the PSR1000 . . .

Why does Yamaha do this to us?

Yamaha can do some pretty stupid things some times... I personally think they bit the big one when they left out the battery option on the 640/740, and you're right in that the case was originally molded to have this. I currently have the PSR-550, and it's not really a bad keyboard, but if you can afford it go for the PSR-1000. That board is better than both the 550 and 640. One HUGE plus is that the 1000 has in internal sequencer with extensive editing as with the 550 and 640 you have a REALLY basic 16 track direct disk sequencer that doesn't really offer much to the user. Another option you might want to consider is Yamaha XG works.... With this you can use the 550 with a computer and have a way better sequencer. Also I think there are many reasons to get the PSE-1000. Sounds a little better, louder speaker system, great large screen like on the 9000, voice creator, which the 640/740 seriously lacked, better sequencing, more storage space for user styles, and so on.. It's an all around better choice.. Plus it's price is fairly decent too..