I was a digital design engineer right out of school, creating multi-layer circuit boards for signal processors and multi-board CPUs. I worked on large government projects and small custom designs.
I started writing firmware to test my hardware designs, and found I had a facility with it. I became the lead firmware engineer on the Micro3200 project. My code was fast and efficient.
The most complex operating system instruction I had to implement was the Block Move instruction. Because it was nontrivial and I spent a week thinking about how to do this, the code, when it was finished, ran perfectly the first time. Our machine outperformed the flagship computer in benchmarks, because my algorithm was more efficient.