Prologue: Getting the cradle ready

Mon, 12 Oct 2026 00:00:00 +0000

Start with an empty program · Completed code

I want to build a transformer inference engine in C# and explain it as it grows. There is a lot of material that shows how to get a model to generate text. I’m interested in the work inside those calls: how the data gets to the GPU, what each kernel does to it, and how those operations eventually produce the next token.

We’ll work through that a piece at a time, following the approach Jack Crenshaw used in Let’s Build a Compiler!. Each lesson adds something to the same running program. We’ll introduce the arithmetic when we need it to understand the code we’re writing, with small examples we can check for ourselves. You should be comfortable reading C#. You don’t need to arrive knowing how a transformer works.

GPU on Andrew Hunter — Systems Architect & Builder

Prologue: Getting the cradle ready