Chapter 3 shows that the program code, program data, and system stack occupy the physical memory after program initialization completes. Either the RTOS or the kernel typically uses the remaining physical memory for dynamic memory allocation. This memory area is called the heap. Memory management in the context of this chapter refers to the management of a contiguous block of physical memory, although the concepts introduced in this chapter apply to the management of non-contiguous memory blocks as well. These concepts also apply to the management of various types of physical memory. In general, a memory management facility maintains internal information for a heap in a reserved memory area called the control block. Typical internal information includes:

· the starting address of the physical memory block used for dynamic memory allocation,

· the overall size of this physical memory block, and

· the allocation table that indicates which memory areas are in use, which memory areas are free, and the size of each free region.

This chapter examines aspects of memory management through an example implementation of the malloc and free functions for an embedded system.