Int 27h                 Terminate and Stay Resident                Superseded

    Ends the current program by returning control to its parent
    program, but it leaves the program in memory and preserves such
    program resources as open files and allocated memory.

        Note    Int 27h has been superseded. Programs should use
                Keep Program (Int 21h, function 31h).

        Entry   CS = Segment of PSP
                DX = Size of resident portion, in bytes

        Return  This interrupt does not return

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    This interrupt is intended to be used by .COM programs. When a
    program issues Int 27h, the CS register must contain the segment
    address of the program segment prefix (PSP).

    Int 27h carries out the following actions:

    - Sets the new size of the program by converting the value passed
      in the DX register to a corresponding number of paragraphs and
      reallocating the program memory. Program memory includes only
      the PSP and program data and code. The reallocation does not
      affect the program's environment block, nor does it affect the
      memory allocated by the program after it was loaded.
    - Flushes the file buffers but leaves files open.
    - Restores interrupt 22h, 23h, and 24h vectors from the addresses
      saved in the PSP.
    - Transfers control to the address specified by offset 0Ah
      (termination address) in the PSP.