1. A matrix multiplication apparatus for a graphic display which transforms line segments into a dot pattern and displays a graphic picture corresponding to the dot pattern, the matrix multiplication apparatus comprising: multiplication means for multiplying transformation matrices with each other and for multiplying a coordinate matrix with a transformation matrix; matrix-storing means for storing bit data representative of the elements of the transformation matrices so as to provide multiplicands and multipliers; and a processor for controlling the multiplication means and the matrix-storing means, said processor including means for supplying bit data representative of the elements of the coordinate matrices to the multiplication means as multiplicands; the multiplication means comprising a plurality of groups of serial multiplicators, each multiplicator processing in sequence a predetermined bit length not less than a bit length of the coordinate matrix element and less than a bit length of the transformation matrix element, each multiplicator having a direct-connection terminal for receiving the multipliers from the matrix-storing means and a cascade terminal, first change-over means for connecting the plurality of multiplicators of the different groups in a cascade connection at the cascade terminals so as to receive the multiplicands representative of the transformation matrix elements from the matrix-storing means in sequence and for enabling the multiplicators to operate independently of each other to receive the multiplicands representative of the coordinate matrix elements from the processor in sequence, second change-over means connected between the matrix-storing means and respective ones of the direct-connection terminals for multiplexing the different multipliers fed from the matrix-storing means so as to enable the cascade-connected multiplicators to process the different multipliers, and addition means for adding the results of the multiplications obtained by the multiplicators belonging to the same groups; the matrix-storing means being directly connected to the multiplication means and comprising random access memories having a predetermined number of blocks corresponding to the number of transformation matrix elements, each block being divided into at least one area which stores whole bits of one element of one transformation matrix, high address setting means for designating the area, and low address setting means for serially reading out the bit data representative of the transformation matrix element stored in the designated area from the least significant bit.