Sharp EL-307 | Pocket calculators, Slide rule, Old technology
Vintage Sharp Compet CS-2109A Electronic Calculator Made in Japan VFD 1976-79 | eBay
File:Vintage Sperry Remington Electronic Pocket Calculator, Model 833-GT, VFD, Made In Japan, Circa 1975 (14111971727).jpg - Wikimedia Commons
Peter's z80.eu site blog - New toy: Texas Instruments LED/VFD Display Calculators (1972 - 1980)
File:Vintage Radio Shack Electronic Pocket Calculator, Cat. No. 65-638A, Model EC-495, 12 Digit Green VFD, Made in Taiwan, Circa 1978 (11972057203).jpg - Wikimedia Commons