Free DOS Memory Block


                 This function  frees memory  that was allocated through
                 the Allocate DOS Memory Block function.

            To Call

                 AX = 0101h
                 DX = Selector of block to free

            Returns

                 If function was successful:
                 Carry flag is clear.

                 If function was not successful:
                 Carry flag is set.
                 AX = DOS error code:
                      07h  memory control blocks damaged
                      09h  incorrect memory segment specified

            Programmer's Notes

                 o    All descriptors allocated for the memory block are
                      automatically freed  and therefore  should not  be
                      accessed once the block is freed by this function.