I make it 8
Pi Models:
A,
A+
B 256MB,
B 512MB,
B+,
Pi2B,
Pi3
Compute Module
(I'm not including the red PCB and very rare blue PCB specials and I think you could further refine the list into the minor revisions)
Pi Models:
A,
A+
B 256MB,
B 512MB,
B+,
Pi2B,
Pi3
Compute Module
(I'm not including the red PCB and very rare blue PCB specials and I think you could further refine the list into the minor revisions)