A Brief History of Math Related Communications

Useful Codes
Numbers 0..9.0 in Morse Code:
.---- ..--- ...-- ....- .....
-.... --... ---.. ----. -----

ASCII character codes: A-Z upper and lower, 0,9. Special characters useful for algebra: Division: x/y. Power x^2. Square Root: x^0.5
Fortran Programming: Multiply: X*Y, Square Root: SQRT(x).

Type Setting
A well argued and damning critique of TeX:
The TeX Pestilence , by Xah Lee, 2004-08.

Geographic contour maps an early application of visualisation of 3D data in 2D.
Wikipedia, on Contour Line shows a contour plot of the function f(x)=sin(x2+y2)cos(x)sin(y).