🚀 go-pugleaf

kr@jet.uk (Kenneth Reed) writes:

>For example, take 2 processes writing to a file "simultaneously". They
>both come along and find out what blocks are free and let's assume
>that the information stays withing the DOS buffers so they don't need
>to go back to disk again. What stops both processes trying to use the
>same "free" blocks?

Think about this:  Suppose you open two files in a standard DOS program,
how does does "know" not to write the two files on top of each other?
Answer:  Because it's DOS and it manages the disk access.

I think what you're missing is that there are not multiple versions of
DOS running in virtual machines.  OS/2 does that.  Windows actually
shares the memory image that exists in the machine at the point where
you typed 'WIN', so all TSR's, including DOS, are shared by all DOS
boxes that you open in Windows.  It's the same DOS running in each box.
So when you run muliple DOS boxes, DOS just thinks you are running a
program called Windows which has a helluva lotta files open.

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