  In today's age of digital technology, ethical concerns regarding computing
systems are increasing. While the focus of such concerns currently is on
requirements for software, this article spotlights the hardware domain,
specifically microchips. For example, the opaqueness of modern microchips
raises security issues, as malicious actors can manipulate them, jeopardizing
system integrity. As a consequence, governments invest substantially to
facilitate a secure microchip supply chain. To combat the opaqueness of
hardware, this article introduces the concept of Explainable Hardware (XHW).
Inspired by and building on previous work on Explainable AI (XAI) and
explainable software systems, we develop a framework for achieving XHW
comprising relevant stakeholders, requirements they might have concerning
hardware, and possible explainability approaches to meet these requirements.
Through an exploratory survey among 18 hardware experts, we showcase
applications of the framework and discover potential research gaps. Our work
lays the foundation for future work and structured debates on XHW.
