Warp wrote:
>   That's why the "memory free" number doesn't really say anything.

Interestingly...

The Amiga OS, when unable to satisfy a request to allocate RAM(*), would 
loop through all the loaded libraries and invoke in each the standard 
entry point intended to unload the library from RAM, then try again. If 
someone still had the library open, the library would refuse to free() 
its memory of course. If the library was closed, it was supposed to call 
free() on any memory it had allocated, and then free itself (via some 
mechanism I don't recall 20 years later offhand).

There was one library that would cache stuff for you (disk pages, if I 
recall), and when the "unload" entry was called, would free the memory 
in the cache without actually exiting.  Another one let you register 
with that library, and when *it* got the unload call, it would pass it 
on to everyone who had registered, so you could (say) trim the undo 
stack down some rather than crash some other program.

Overall, a pretty cool functionality for such a simple mechanism. It's 
amazing how flexible AmigaOS was, simply by having a handful of 
primitives that it *didn't* try to combine for you into what the 
designers thought you'd want to do.


(*) In the good old days, back before desktop CPUs handled page faults...

-- 
   Darren New / San Diego, CA, USA (PST)
     Remember the good old days, when we
     used to complain about cryptography
     being export-restricted?

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