Yeah, David Paich said pretty much the same thing in the Oct '82 issue of Keyboard magazine:
"On "Africa" you hear a combination of Steve's dad playing marimba combined with GS-1....the kalimba is
all done with the GS-1. It's six tracks of GS-1 playing different rhythms. There's a high organ sound that's GS-1 and I wrote the song on the CS-80 so that plays the main part of the entire tune.
Paich onstage with Toto back in 1982 (clockwise from lower left): Yamaha GS-1, Yamaha CS-80,
Roland Jupiter-8 and Steinway D grand piano.
In the same article/interview Steve Porcaro mentions that he just modified existing programs in the GS-1; "You load a strip into it and the programming module (there's only one in the United states) shows what the program looks like on four video screens. I would just start dicking with it, isolating different sections and seeing where different parts of the sound were coming from. I've always been attracted to those kind of instruments because I come from being a piano player. I love the touch sensivity, but from a synthesist's standpoint the non-programmability doesn't bother me all that much, because some of the sounds in it are just too kick-a*s to ignore."
"The (Yamaha) CS-80 is a step ahead in keyboard control, and a generation behind in digital control" -- Dan Wyman, Jan 1979