Before GLSL, before HLSL, at the dawn of shader programmability, there was the ARB assembly language. Here is a complete Visual Studio 2015 solution to build an OpenGL application which uses assembly language shaders. And yes: writing an assembly language shader is just as time-consuming and error-prone as you would expect! But if you love 3D graphics, you'll probably also be keen on the history of OpenGL, Mesa, DirectX, nvparse and the like.
Refer to the Authorship directory for notes on attribution of the original NVIDIA sample code.