Nigel,

It appears he is using a Sequential Circuits Prophet 10, which was a dual manual Prophet 5 (actually two Prophet 5's in one case) and he's using nearly the same patch as he used on both Sundown Slowdown and Valerie.

His Hammond organ work is also very tasty (usually simple but very effective) and he's not too shabby on the guitar as well.

I believe some of Stevie Wonder's best work was when he was using the Yamaha GX-1 (he called it his "Dream Machine") on his "Songs In The Key Of Life" album, and one of its many uses was to get a cool string section effect on Village Ghetto Land.

I was very fortunate to get an opportunity to play the legendary GX-1 at Yamaha's Head Office back when I was a teacher in the Electone School, and, although I didn't get to play a Prophet 10, I did get to use a beautifully well maintained (and far more common) Prophet 5 for a few months when doing recording sessions at a studio in Newfoundland.

Back in the day, these instruments (and their derivatives) were on many top albums and used by some very notable (and very capable) players.

The GX-1 weighed over 600 lbs (not including the 200 lb pedal board), certainly not something a One Man Band player would be schlepping around without the help of several strong roadies and a very big van, not to mention paying the huge price tag of $50,000 (in 1980's dollars).

A Prophet 10 was a far more svelte 150 lbs, but didn't have a drum machine (analog) like the GX-1.

Man, I don't know how wandered into this stuff since the post was initially about vocals , but, I suppose singers (and songwriters) will reap the benefits of having great backing instruments.

Ian