The California Technology International MR 2000 was powered by a Z80 CPU and in theory could have been "upgraded" to run BASIC if the manufacturer wanted to do this, but alas true laptops were still a few years away. The MR 2000 came out in 1979 or 1980. Click image for larger view.
The first PDAs came out in the late 1970's, most of which were calculators with memory and simple notes, calendar, address book type functions. CTI took this concept in a different direction with its PDA's. Their concept was born in the MR 2000, which looks like the early laptop computers of the same footprint that came out a year or two later. On the continuum of portable devices the MR 2000 fits perfectly into the flow of developments of the times.