C: structure padding, packing, 4 programs {reversing array, swapping bits, 2 array problems}, build process, storage classes, type qualifiers (volatile), pointers, DMA, program memory layout. OS: process vs thread, POSIX, 1 threading code using mutex, critical section and race condition, IPC and shared memory, interrupts. RTOS: priority inheritance and inversion, discussions on FreeRTOS apis.