Op 29-1-2013 20:02, Michael B. Brutman schreef:

> PC/MS DOS 5.x and 6.x will run in 256K with usable memory to spare.
> PC/MS DOS 3.x will run in 128K with usable memory to spare.  If FreeDOS
> is designed/optimized for a bigger footprint then that's fair, but there
> is nothing wrong with asking or trying to push the limits.
> So make it 256K.  Fine.  The point (which you missed by a country mile)
> is that it should run on a fairly small machine.  Because they are out
> there ...  And no, 35 years ago would put us in 1978.  128K/256K PC
> style machines were common even in 1985/1986. FreeDOS does not add that
> much extra function where a 256K (or even a smaller machine) could not
> be a reasonable target.

Boot FreeDOS on a modern machine (or emulator) without loading an XMS 
driver. You'll see about 56KB for kernel (likely config.sys settings can 
reduce memory if manually specifying a lower amount of buffers/files 
etc) and FreeCOM using about 101KB (which you can't reduce, even if 
loading an XMS-manager from commandline).

That makes 157KB, without having loaded drivers and loaded programs.
Though compiled versions of FreeCOM exist that can swap large parts of 
shell to disk upon executing a command, my bet would be on the shells 
used by embedded ROM-DOS or so. 4DOS also is able to swap to disk (256KB 
swapfile) in order to preserve memory for starting/running programs.

Out of the remaining amount of conventional memory, I've got no idea 
what's still able to run and what not. Only ever used machines that had 
at least 640KB available. Any emulator available that allows to set CPU 
below 386 and total system memory capacity at a user-selected value 
below 1024KB ?


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