I beg to differ, both by date and company. In February of 1972, Hewlett-Packard (HP) introduced the HP-35 ($395), the first practical, general production, hand-held, scientific calculator. In November of that same year, Texas Instruments (TI) introduced its SR10 ($149) "Slide Rule" Calculator. In 1975, the Keuffel and Esser company ceased its manufacture of its formerly very popular Deci-Lon lines, the ten-inch "regular" (Deci-Lon 10) and five-inch "pocket" (Deci-Lon 5).
My first calculator was a $100+ 4-banger brick of un-recallable name but I moved to the first HP-25 in '75 and updated as new models came along until my last and still best HP-200LX. I still use this jewel on a frequent basis even though I have an iPod Touch and other gadgets. It had the near-ultimate PIM (Personal Information Manager) that I have yet to see the equal let alone superior.
[Sorry TI fans, I could not resist. And for the HP Management IDIOTS who bowed to Microsoft and killed the great HP Calculator Division, eternal shame!]
I went to college in 1973 and most of the chemistry students I was with had SR10’s. A few of the Electrical Engineers had HP-35’s. I was stuck with a Texas Instruments TI-2500, a four-banger that cost me $79.99 and can’t do a tenth of what my $3 Casio wristwatch can today.
Yes, my Dad was an engineer and brought one home from work. I took it to my HS Physics class and wowed the teacher.
Fair enough, but it was the hand held scientific calculator that was a milestone in engineering.
TI was one of the leaders in that field.