Hardware-based courses in computer science studies require much effort from both students and teachers. The most important part of students' learning is attending in person and actively working on laboratory exercises on hardware equipment. This paper deals with a specific group of students, those who are marginalized by not being able to regularly attend lessons and perform the laboratory exercises. This group of "busy students" includes older students, and those who travel, are employed or are parents. In particular it describes how such students achieved impressive results in a hardware-based course by using Open Educational Resources (OER). These facilitated students' learning process and gave busy students the opportunity to organize their learning time so as to work on the hardware courses remotely from home when they had time and opportunity. The results of the evaluation show significant improvements, both in grade distribution and course throughput, after implementing the new Open Educational Resources approach.