My first number cruncher was a 1978 Sharp PC-1201, an (as the brochure says, capitals included) "Computer-Like 10-Digit Scientific Calculator with 128-Step Programming". It featured a very readable blue-greenish VFD display and ran on either 2 AA-cells or the included rechargeable battery pack, retaining the 128-step program when turned off (it even included a backup coin cell).
Such was its power that I astonished the guy who had to calculate the mortgage payments for my first house by having the results for the full 30-year period ready when he was still skipping through his "professional" paper tables ! I still have the machine, and the original brochure that was forwarded at my request straight from Sharp/Osaka.
A few years later the PC-1500 blew its predecessors away, especially because it was so well documented (both its hardware and the machine language used "underneath" its very comprehensive Basic).