Zak Kohler

An educational introduction to developing Embedded C products using simulated hardware aimed at beginners. I explore the line between hardware and software by creating a series of demos within a minimal, free, open-source environment. These demos span from blinking an LED to implementing pieces of a toy operating system. The goal is to shed light on the parts of the system that we take for granted and gain a better understanding of computers and operating systems.

I was the sole developer of the code examples and compilation instructions, along with a blog post and LinuxFest 2020 conference talk on the subject. This lowers the barrier of entry for new Embedded C and ASM developers while adding to the ecosystem for open hardware standards such as RISC-V.

A conference presentation covering my own micro-programmable CPU simulator. The goal was to teach how CPUs work internally and how they interface to the rest of a computer. I was the sole developer of the interactive framework that allows single-stepping through microcode, assembling from a custom assembly language, and performing simple IO. I was also the sole contributor to this project, which I presented at the PyOhio 2019 conference.

My talk, "Learn How Computers Work Between Silicon and Assembly: Build a CPU with Python," helps high-level programmers understand what is happening in a computer at a lower level. During the talk, we build up a CPU focused on transparency, interactivity, and modularity. Our CPU has a configurable architecture and machine language, and it is extensible with new instructions to add functionality. The talk covers registers, data and address buses, memory (ROM and RAM), IO, and assemblers.

Explore the line between hardware and software by writing code with absolute control over the CPU and peripherals. We'll explore how to do this using a completely free and open source simulator (Renode), toolchain (GCC), and instruction set (RISC-V). Using assembly, we'll initialize system parts such as CPU interrupts and privilege levels. Finally, we'll review the assembly code for doing a context switch, the key software which enables multitasking via timesharing.