AMC-OS Loader Memory management

Memory used during AMC-OS Loader execution

AMC-OS Loader uses only the first megabyte of memory :

00000-003FF	Real-mode interrupt table
00400-00500	BIOS static data
00501-005FF	Free (unused)
00600-007FF	Master boot record
00800-[__A]	Kernel static data (initialized by boot loader)
[__A]-[__B]	AMC-OS Loader code
[__B]-[__C]	AMC-OS Loader picture
[__C]-077FF	Free for allocation
077FF-07BFF	AMC-OS Loader stack
07C00-07DFF	Boot loader code (VBR or MBR for floppy disk)
07E00-07FFF	Free (unused)
08000-9[_D]	Free for allocation
9[_D]-09FFF	Extended BIOS data area (EBDA - optional) } Memory management Initialization During memory initialization process (AMCOSLDR_InitFirstMegabyte), AMC-OS Loader : looks for EBDA using interrupt 12H and value stored in 0040:000E to get highest pointer in memory [_D] calculates the values of [__A] to get lowest pointer in memory creates a linked list of available blocks of memory (AMCOSLDR_Malloc_Entry) initializes two blocks of available memory (marked Free for allocation in previous table) Allocation Three functions are available to AMC-OS Loader for memory allocation : AMCOSLDR_DefinitiveAlloc : Used to allocate memory that shall stay at this place at the end of the process (used by kernel afterwards). Memory will be taken from bottom of free memory. AMCOSLDR_TempAlloc : Used to allocate memory that will be freed at the end of the process (eraseable by kernel afterwards). Memory will be taken from top of free memory. AMCOSLDR_VolatileAlloc : Used to allocate memory for immediate use (valid only until a new call to any memory function is made). Memory will be taken from top of free memory. The two first functions maintains the linked list of available blocks of memory.