ALERT: The osal-4.2.1a release package is now available. This release package fixes a unit test makefile to use Modules.mak rather than using ut-modules.mak directly. The top-level readme.md file was also updated to add missing information. The OS Abstraction Layer (OSAL) project is a small software library that isolates embedded software from the real time operating system. The OSAL provides an Application Program Interface (API) to an abstract real time operating system.