hereinafter , a printer system with an image processing unit of the present invention will be described below in detail with reference to the attached drawings . fig1 is a block diagram showing the structure of a printer system according to the first embodiment of the present invention . referring to fig1 the printer system is composed of a first host computer 15 , a second host computer and a printer 1 which are connected through a network , communication line or bus to each other . the printer 1 in the first embodiment is composed of a receiving section 2 , an editing section 3 , first to n - th display list storage sections 4 to 6 , first to n - th drawing sections 7 to 9 , first to n - th frame buffers 10 to 12 , a print mechanism section 14 , and a print control unit 13 . the receiving section 2 receives print instructions . the editing section 3 produces a display list from the received print instructions in units of bands which are cut in a main scanning direction of a printing operation . the first to n - th display list storage sections 4 to 6 store the display lists produced in units of bands by the editing section 3 . each of the first to n - th drawing sections 7 to 9 carries out drawing operations in accordance with the drawing instructions of the display list which has been stored in a corresponding one of the first to n - th display list storage sections 4 to 6 . the first to n - th frame buffers 10 to 12 store bit image data drawn by the first to n - th drawing sections 7 to 9 . the print control unit 13 controls the print mechanism section 14 in response to a drawing operation end notice such that bit image data which have been stored in the frame buffers 10 to 12 are printed . also , the first drawing section 7 , the second drawing section 8 , the n - th drawing section 9 are possible to carry out the drawing operations independently from each other using a cpu or coprocessor other than the cpu for controlling the whole printer , respectively . next , the operation of the printer system of fig1 in the first embodiment will be described with reference to fig2 fig3 and fig4 . the printer 1 receives print data or a sequence of drawing instructions from a host computer 15 or 16 connected with the network through the receiving section 2 ( step 20 of fig2 ). at this time , the editing section 3 receives the sequence of drawing instructions from the receiving section 2 , and carries out an analysis and edition process to the sequence of drawing instructions . in the analysis and edition process , the editing section 3 calculates a time cost of each of the drawing instructions , i . e ., a time required to execute the drawing instruction . then , the editing section separates the sequence of drawing instructions into display lists of drawing instructions based on the number of drawing sections and the calculated time costs . in the analysis and edition process , the drawing instruction decomposing process to be described below is contained . in the drawing process in the printer 1 , the following method is adopted to increase the memory use efficiency of the mounted memories . that is , the sequence of drawing instructions are separated along y direction in fig3 a into a direction parallel to a main scanning direction ( x direction in fig3 a ), and a print region corresponding to the sequence of drawing instructions is divided into blocks ( to be referred to as bands , hereinafter ). therefore , the bands may be equal to each other in height . in this case , the drawing operation and a memory area management become easy . also , the bands may be different from each other such that the drawing operation times by the drawing sections are approximately equal to each other . at this time , the editing section 3 decomposes each of the drawing instructions of the sequence when a figure or drawing extends over two or more bands . that is , the editing section 3 decomposes the drawing instruction in accordance with the band height to make a redundant drawing operation minimum . the drawing operation is carried out to a corresponding one of the frame buffers 10 to 12 by a corresponding one of the drawing sections 7 to 9 . for example , as shown in fig3 a , a full image data corresponding to the sequence of drawing instructions is divided into band image data with the height of 50 . it is supposed that a rectangle drawing instruction rect ( 40 , 20 , 450 , 9 ) is contained in the sequence of drawing instructions to draw a rectangle with a line width 1 over the band 1 and the band 2 . in this case , the rectangle drawing instruction rect is divided into line drawing commends line ( 40 , 20 , 40 , 50 ), line ( 40 , 20 , 450 , 20 ) and line ( 450 , 20 , 450 , 50 ) for the band 1 and line drawing instructions line ( 40 , 50 , 40 , 90 ), line ( 40 , 90 , 450 , 90 ) and line ( 450 , 90 , 450 , 50 ) for the band 2 , as shown in fig3 b ( step 21 of fig2 ). in this way , an instruction decomposing process is carried out to each drawing instruction over the bands based on the number of drawing sections and the time costs . the display lists of drawing instructions obtained through the instruction decomposing process are stored in the display list storage units 4 to 6 ( step 22 of fig2 ). in the above - mentioned editing process , when the display list is completed for every band , each of the drawing sections 7 to 9 starts the drawing operation in order from the completed display list for every band in response to a drawing operation start instruction from the editing section 3 . when the drawing operation for the display list of drawing instructions is ended , each of the drawing sections 7 to 9 starts the drawing operation to the other display list which has been completed but not yet drawn . this operation is repeated ( steps 23 to 24 of fig2 ). when it is confirmed that the drawing processes for all the bands , the printing operation is started by the printer controller 13 in response to a printing operation start instruction ( step 25 of fig2 ). at this time , because the printer 1 has the n drawing sections from the first drawing section 7 to the n - th drawing section 9 , the n drawing operations at a maximum are possible to be carried out in parallel . as a result , the drawing operation can be carried out at high speed . also , at this time , in fig1 the editing section 3 produces the display list for every band , and the plurality of drawing sections 7 to 9 carry out the drawing operations based on the display lists . the frame buffers 10 to 12 are sufficient to have a storage capacity for the band , so that the frame buffers 10 to 12 can be made small . however , when each frame buffer has the storage capacity for one frame , the degree of freedom in the separating operation of the sequence of drawing instructions by the editing section 3 can be increased . next , a printer of the printer system according to the second embodiment of the present invention will be described with reference to fig4 . referring to fig4 the printer 1 is composed of a first cpu 41 , a main memory 43 , an interface ( i / f ) section 40 , drawing processors 44 to 46 , and local memories 47 to 49 . the first cpu 41 controls the whole printer 1 . the main memory 43 is a storage section for the first cpu 41 and is necessary to manage data processing and the printer operation . the interface ( i / f ) section 40 receives the print data or the sequence of drawing instructions from a network . the drawing processors 44 to 46 carry out the drawing operations to the local memories 47 to 49 in response to the drawing operation start instructions from the first cpu 41 , respectively . the local memories 47 to 49 correspond to the frame buffer 10 to 12 in fig1 . first , the first cpu 41 receives the print data or the sequence of drawing instructions from the host computer through the i / f section 40 ( step 20 of fig2 ). at this time , the first cpu 41 carries out - only the start control and state control of a dma controller which is in the i / f section 40 , so that the processing load on the first cpu 41 is light . the first cpu 41 can execute another processing in addition to the above control . the first cpu 41 decomposes the sequence of drawing instructions in units of bands in approximately parallel to the data reception ( step 21 of fig2 ) to carry out the editing process so that the display list is produced for every band ( step 22 of fig2 ). at this time , the produced display list for each band is written in the main memory 43 which can be accessed by the first cpu 41 and the plurality of drawing processors . each time the production of the display list for each band is completed , the first cpu 41 issues the drawing operation start instruction to any of the drawing processors 44 to 46 . the drawing processors 44 to 46 start the drawing operations of the corresponding ones of the bands in response to the drawing operation start instructions , respectively ( step 23 ). because the drawing operations are respectively carried out to the local memories 47 to 49 by the drawing processors 44 to 46 , the drawing operations can be carried out in parallel to each other . when completing the drawing operations , each of the drawing processors 44 to 46 notify to completion of the drawing operation to the first cpu 41 by use of an interrupt signal , and the first cpu recognizes that the drawing processor which has issued the interrupt signal is free . the first cpu 41 checks whether any display list is remained in the main memory , in response to the interrupt signal . when there is any display list in the main memory , the first cpu 41 issues the drawing operation start instruction to the issuing drawing processor again . this operation is repeated ( step 23 to 24 ) and the drawing process for one page is ended . at this time , the printing operation start instruction is issued from the first cpu 41 to the mechanism section 50 and the printing operation is started ( step 25 ). in the above - mentioned structure , the drawing processor carries out the drawing operation . however , the drawing operation may be carried out by a coprocessor or a custom lsi with a drawing function . also , in the above description , the printing operation is started after all the drawing operations are completed . however , the printing operation of an image to the print mechanism section may be carried out in parallel to the drawing operations for the display lists of the bands , in case where it is possible to carry out the drawing operations at high speed sufficiently rather than the printing operation . next , the printer system according to the third embodiment of the present invention will be described below with reference to fig5 . referring to fig5 in the printer system according to the third embodiment of the present invention , the printer 56 has basically the same structure as the printer 1 shown in fig1 . in the third embodiment , the host computer 51 of fig5 includes an application program 52 for producing the print data , a printer driver 53 for converting the print data or the sequence of drawing instructions in a printer language which the printer 56 is possible to analyze , and a band separating section 54 for dividing the sequence of drawing instructions in the printer language in units of bands . the host computer 51 is connected with the printer 56 through the network , as in fig1 . next , the operation of the printer system in the third embodiment of the present invention will be described below . in the host computer 51 of fig5 the application 52 operating on the host computer 51 produces the sequence of drawing instructions as the print data . the printer driver 53 converts the sequence of drawing instructions in the printer language which the printer 56 is possible to analyze . the band separating section 54 divides the sequence of drawing instructions into the display lists of drawing instructions in units of bands . the band has a height easy for the printer to process the display lists of drawing instructions . on the other hand , the display lists of drawing instructions are transmitted to the printer 56 through the transmitting section of the host computer , and the printer 56 receives the display lists of drawing instructions . in the third embodiment , because the sequence of drawing instructions already divided in units of bands is transmitted , there is not necessary the band dividing or separating process by the editing section in the printer 56 . the display lists can be distributed to the drawing sections in the printer 56 at very high speed . in the above description , when a display controller is used in place of the printer controller 13 and a display unit is used in place of the mechanism section 14 , the present invention can be applied to the image processing system . as described above , according to the printer system of the present invention , the printing process efficiency of the printer is improves by providing the plurality of drawing sections . the drawing time can be reduced because the plurality of drawing processor operates in parallel . also , it becomes possible to select the hardware structure in accordance with a requested efficiency because the drawing time can be short in accordance with the number of drawing processors . this is because the estimation of the drawing time by the editing section is proportional to the number of drawing sections .