winscape 2268

What he's getting at is there isn't any hardware protection available for DOS- at least on the pre-286 x86 cpus, and due to the design buttumptions of the OS and applications, its not feasible to implement in any comprehensive way on the newer cpu's. About the best way to make DOS less of a problem is to set up virtual x86 machines, each protected from the other, with a monitor thats able to reset-restart them when they crash. Windows mostly succeeds in doing this, though bugs remain and is still lots less user friendly than a shell in X windows.

DOS's memory protection in software is pretty much limited to putting allocation control data before chunks of memory so freed regions can be concatenated. In DOS there is no way to stop any program from writing any ram location, and in fact programs were encouraged to do just that- lots of OS internal data is exposed for programs to use.

Towards the end of DOS's mainsteam use here were utilities the user could run that were capable of scrubbing various parts of the OS when programs terminated to help keep the OS from coming unglued- but its really so bloody primitive that theres no much you can do to make it more stable.

Gregm