Back in the old days of the original AmigaOS, the system used to allocate areas of unused memory to new tasks was pretty simple. The size and position of blocks of free memory were kept in a list, and when memory was needed the system would traverse this list until it found a block that was sufficiently large. This block was then split, one part returned by the allocator for use, while the other part (whatever part of the block wasn't needed) was left in the free list. This method served its purpose well enough at the time, but with the increased demands of modern computing - and of course our desire to bring this new version of the Operating System to the cutting edge - AmigaOS4.0 has introduced a better way of doing things.

In a previous item, we described how the AmigaOS4.0 memory system works in terms of managing memory allocations from the top. However, there is more to allocating memory than that. The object caches of course work on memory that has already been mapped into the virtual memory space. But both the virtual address ranges, as well as the physical memory has to come from some source, too.