Alexis de Tocqueville Institution it called "hybrid" source models, in which true open source code is mixed with proprietary code, with the result that intellectual property rights are nullified. To illustrate potential problems with this approach, the book cited the case of Linus Torvalds, creator of Linux. It claimed Torvalds used source code taken from Minix, a small Unix-like operating system used in teaching computer science, to create Linux 0.01, on the theory that no mere student could write an entire Unix-like kernel single-handedly — although writing a kernel of similar size and capabilities is a standard part of many computer science degrees. These
Operating system device drivers to the operating system's kernel, where they can be passed onto applications, or carried out directly. Security of operating systems has long been a concern because of highly sensitive data held on computers, both of a commercial and military nature. The United States Government Department of Defense (DoD) created the "Trusted Computer System Evaluation Criteria" (TCSEC) which is a standard that sets basic requirements for assessing the effectiveness of security. This became of vital importance to operating system makers, because the TCSEC was used to evaluate, classify and select trusted operating systems being considered for the processing, storage