winscape 2367

Back in the early Windows days they had a weak form of it- although the OS was still running essentially in real mode, you could allocated blocks of memory & get a descriptor back. When you "locked" the descriptor, the OS would return a base address & you could use the memory. When "unlocked", the OS was free to page out the data. You were not supposed to try a deref the memory while the block was unlocked and you had to buttume a different base address might be returned when the descriptor was locked later on. Its a good beginning, and its enough so real vm hardware can be brought to bear on allocated objects to manage protection better. They say in older versions of Windows, the OS would literally fwrite() the buffer out to the pagefile- heaven help us.

OTOH, as one might expect, in later versions of Windows the memory allocation routines have diversified & the older functions deprecated, now you can choose from at least 3 different ways to allocate memory from the OS- and its anyone's guess which (or how many) of these interfaces will themselves be deprecated in the next releases of Windows. Its as if there is no coherent architecture and Microsoft is just making this crap up as they go.

Gregm