AH = 58h
        AL = function code
            0 = get allocation strategy
            1 = set allocation strategy
               BL = strategy code
                   0 first fit (use first memory block large enough)
                   1 best fit (use smallest memory block large enough)
                   2 last fit (use high part of last usable memory block)
Return: CF = 1 error
            AX = Error Code
        CF = 0 successful
            AX = strategy code
Note: the Set subfunction accepts any value in BL; 2 or greater means last fit.
      the Get subfunction returns the last value set, so programs should check
      whether the value is >= 2, not just equal to 2.
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