Atari systems support two kinds of memory. Standard RAM (referred to as ST-RAM) is general purpose RAM that can be used for any purpose including video and DMA. Current Atari architecture limits the amount of ST-RAM a system may have to 14MB.

Alternative RAM (referred to as TT-RAM) can be read and written faster than TT-RAM but, as the DMA chip can't access this RAM, it can't be used for video memory or DMA transfers.

The Malloc() and Mxalloc() calls allocate memory blocks from the system heap. Malloc() chooses the type of memory it allocates based on fields in the ProgramHeader?. Mxalloc() allows the application to choose the memory type at run-time.

Memory allocated with either Malloc() or Mxalloc() may be returned to the system with Mfree(). Memory allocated by a process is automatically freed when the process calls Pterm().

MultiTOS? and MiNT (when run by 68030 processors or above) use memory protection to prevent an errant process from damaging another. It is possible with Mxalloc() to dynamically set the protection level of an allocated block.

MagiC? doesn't use memory protection.