According to Wikipedia, the TRS-80 Model 100 sold 6 million units.
This number seems very high. In fact, our former Dear Leader, Jeff Atwood wrote:
wow, they sold six million portable TRS-80s? http://en.wikipedia.org/wiki/TRS-80_Model_100 I'm calling {{citation needed}} on that.
Is there documentary evidence to support the 6 million unit figure?