A mathematics room of a grammar school in Leeds on a sunny afternoon, on a wooden desk a long flat calculator seventeen centimetres long with a black frame, in its upper third a large almost square pale grey-green display window crossed by one thin smooth wave-shaped line in dark grey, below it a silver-grey key field with cream-white and black keys, one orange key and one red key, every key plain, smooth and unmarked, beside it a sheet of fine squared paper with the same wave drawn by hand in pencil, a hand in a navy jumper sleeve holding the pencil at the end of the curve, low sunlight from the left.
What it was used for
According to its own corporate history Casio released the graphing scientific calculator fx-7000G in August 1985. On a liquid crystal display of 96 x 64 dots it draws the graph of a function and shows tabular values as a bar chart, with, according to its developer, coordinate readout and zoom; a menu with icons was, as he recalls, being considered at the time. It was meant for and used in teaching: Casio names its use as a learning tool in the USA, France, Germany and Australia and the device's entry into the collection of the Smithsonian Institution. By the company's development account the project goes back to a one-page proposal of 1983.
What was new
Casio itself calls the machine the world's first graphing scientific calculator. The difference from what existed: the calculator drew the course of a function on the device itself instead of giving numerical values that had to be plotted by hand. The barb lies in what that cost - in power. In Casio's account the developer Hiroyuki Yoshino describes needing a full-dot display to draw the graphs properly, which would have raised consumption; the team solved it with a dot-matrix LCD and a low-power design.
What the sources leave open: Both sources are Casio's own pages: the corporate history (August 1985, 96 x 64 dots, the priority claim) and the development account with Yoshino. Neither gives price, program steps or production figures. The world-first claim is therefore not independently confirmed.