<p>Recent studies have shed light on the challenges students face in grasping certain aspects of computer science (CS) curricula. According to the threshold concepts theory, specific foundational ideas, if not thoroughly understood, can serve as cognitive barriers that hinder the comprehension of subsequent topics. Within this theoretical framework, the organization of main memory in program execution is suggested as a potential threshold concept in understanding computer operations. The present study aims to examine students’ understanding of topics related to main memory organization, operation, and its role in program execution. It seeks to categorize and elucidate students' conceptions and misconceptions through an analysis of their written responses to open-ended questions as well as through small-group discussions crafted to deepen insights. The development of questions grounded in Kintsch’s text comprehension model theory proved beneficial for uncovering students’ conceptualizations. The findings highlight a prevalent challenge among students in articulating the importance of main memory for computer operations and in establishing a conceptual link between main memory organization and the execution of program instructions. These findings underscore the significance of the proposed threshold concept. In response to the emerging misconceptions, CS educators should provide insight into students' comprehension and devise a comprehensive, integrated instructional approach to tackle the fundamental interrelated CS concepts. This paper offers guidance on approaching the existing educational material and crafting appropriate questions to bolster students' inferential skills and improve overall learning outcomes.</p>