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(11) | EP 0 150 453 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Inter-logical-area data transfer control system |
| (57) An improved inter-area-data transfer control system is disclosed which includes a
display control device provided with an area movement function and is capable of providing
the logical transverse widths of source (SW) and destination (DW) areas (registers
72 and 74) in a logical memory space separately from each other so as to reduce time
required to execute the transfer of data from the source area to the destination area.
The system comprises: means (71) for specifying a transfer start point of a source
area (S); means (73) for specifying a transfer start point of a destination area (D);
means (61) for holding amounts of data to be transferred in a horizontal direction;
means (63) for holding amounts of data to be transferred in a vertical direction;
and, means (72, 74) for providing the logical transverse width of said source area
(S) and the logical transverse width of said destination area (D) separately, characterized
in that a plurality of data of said source area specified by said means are read out
from said memory unit (4) and are sequentially written into said destination area
(D) so as to achieve transfer of said data between said source and destination areas
(S, D). |
BACKGROUND OF THE INVENTION
1. Field of the Invention
2. Description of the Prior Art
[0002] In Fig. 1, there is illustrated a block diagram of a conventional color graphics display system.
[0003] In the illustrated prLor art system, there is provided a CPU (microprocessor) 1 for controlling the whole system, to which are connected a main memory 2 and a display control circuit 3. Main Memory 2 is used to hold programs or data, while Display Control Circuit 3 is dedicated to controlling the display of color graphics. Reference character 4 deúrtes a VRAM (video memory) for holding CRT display data and 5 designates a CRT color display unit.
[0004] Fig. 2 illustrates a block diagram of an embodiment of the display control circuit 3 shown in Fig. 1.
[0005] In this embodiment, clock signals generated by a timing controller 11 are input to a counter,12 which comprises a column counter, a line counter and a row counter. Counter 12 genereates synchronizing signals for CRT display via a display timing circuit 13, while Counter 12 creates display addresses which are output as VRAM addresses by means of a multiplexer 12.
[0006] Read data for display access coming from VRAM 4 is input to a video output controller 20 via a buffer 19 so as to create CRT video signals.
[0007] On the other hand, when VRAM 4 is accessed by CPU 1, the addresses of VRAM 4 are set in a VRAM address register 14. And, if a write strobe is input to a CPU interface controller 18, Multiplexer 15 selects as VRAM addresses the outputs of VRAM Address Register 14 specified by CPUI and then the write data from CPU1 is written via Buffers 16, 17 into VRAM4.
[0008] Fig. 3(A) illustrates a logical memory space and Fig. 3(B) illustrates a physical memory space. As shown in Fig. 3(A), in the logical memory space there are present an operation table area, a display area and a suppcrt message area, and these three areas are started by separate values respectively and are definetely separated from one another. Also, for screen display, as can be seen from the display area shown in Fig. 3(A), there happen some cases where a display including a plurality of superposed window frames is requested from an application software. In these cases, there arises a demand to perform data transfer between these areas.
[0009] Let us take an example in which in the logical memory space shown in Fig. 3(A) the block data of a source area S within VRAM4 is transferred to a destination area D based on the X, Y coordinates. In this case, the above-mentioned source area S is considered as a predetermined area (area covered by leftward-falling oblique lines) in the operation table area, while the above destination area D is considered as a predetermined area(area covered by leftward-falling oblique lines) in the display area.
[0010] CPU 1 calculates a physical address SA of VRAM 4 based on the value of a base address (this is referred to as "Base SB" hereinafter) in the source area S and the start coordinates (SX, SY) and then sets it in VRAM Address Register 14 within Display Control Circuit 3. And, CPU 1 outputs a read command and reads out the color data within VRAM 4 that corresponds to the above-mentioned start coordinates (SX, SY).
[0011] Next, CPU1, based on the Base SB of the destination area to which the block data is to be transferred and its start coordinates (DX, DY), calculates a physical address DA in VRAM 4, and then sets it in VRAM Address Register 14 within Display Control Circuit 3. And, CPU1 outputs the color data and a write command to write them into the locations of VRAM4 that correspond to the start coordinates (DX, DY) of the destination area D.
[0012] With the above prior art system, it is necessary to repeat the above-mentioned read/write operations NX times regarding the horizontal direction and NY times regarding the vertical direction, that is, a total of NX X NY times before the block data of the source area S can be transferred to the destination area D. In Fig. 3(A), reference character sd designates a status display area, sA represents the start coordinates of a support message area, and sB expresses the base value of the support message area.
[0013] The above-mentioned principles, of course, can apply similarly when data is to be transferred in the opposite direction, or when the data is transferred from the support message area to the display area.
[0014] The operation table area shown in Fig. 3 can be changed according to the kind of application software. That is, a very large area may be requested for it or, on the contrary, a small area may be requested. This is so with the support message area. On the other hand, the display area has a fixed size that is determined by way of hardware by CRT Display. In this case, a predetermined window frame is assumed within the display area and a portion to be operated at that time and requiring display is brought into this window frame, while the assumed window frame is requested for displacement according to the conditions. Accordingly, the transverse width of each of the above areas can take on various values logically. Thus, the data to be transferred comprises several divided blocks and the data is also to be transferred between data areas which are different from each other with respect to the distance between the blocks. Such operation can not be processed completely only by the conventional data transfer technique using successive areas which can be dealt with by hardware.
[0015] For this reason, it is necessary to perform the above-mentioned processing by means of software.
[0016] To make a portable size a personal computer and reduce the cost thereof, a conventional display control system for a personal computer is designed such that amounts of hardware, e.g., the number of gates and the number of IC elements regarding the internal structure of a display unit and interfaces are reduced considerably. As a result of this, the loads of the software are increased accordingly in such conventional system.
[0017] With the above-mentioned prior art system, as can be seen from the above example of the block data transfer mentioned above, all of the necessary processings must be performed by CPU 1, requiring a very long time for the data transfer.
[0018] On the other hand, normally, CPU1 and Display Control Circuit 3 are operating independently of each other and also the display timing of Display Control Circuit 3 has a priority over the VRAM access timing of CPU1. As a result of this, in access from CPU 1 to VRAM 4, a wait time is produced, which extremely decreases the efficiency of the data transfer.
[0019] In other words, in the above-mentioned prior art system, since the software must share a greater load in display control, there is a problem that it takes a very long time for the prior art system to execute its operation. Also, in case of a high-grade computer that has increased display specifications and a plurality of display modes, the address calculations in the prior art system become more complicated so that the time necessary for execution of its operation is greatly extended.
SUMMARY OF THE INVENTION
[0020] The present invention aims at eliminating the drawbacks found in the above-mentioned conventional system.
[0021] Accordingly, it is a primary object of the invention to provide an improved inter-logical-area data transfer control system which is capable of reducing the time necessary for execution of its data transfer from a source area to a destination area in its logical memory space.
[0022] In attaining the above object, according to the invention, a display control sytem is provided with an "area movement" function, and, at the same time, the logical transverse widths of the source area S and destination area D are given separately from each other. Interfacing procedures required for this purpose are to be determined and oriented by software
[0023] The above and further objects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for purpose of illustration only and are not intended as a definition of the limits of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024]
Fig. 1 is a block diagram of a commonly-used conventional color display system;
Fig. 2 is a block diagram of a display control circuit employed in the above conventional system in Fig. 1;
Fig. 3(A) is a schematic view of a logical memory space;
Fig. 3(B) is a schematic view of a physical memory space;
Fig. 4 is a block diagram of an embodiment of the invention;
Figs. 5 and 6 are schematic views respectively illustrating the contents of registers employed in the above embodiment;
Fig. 7 is a table of command codes employed in the present invention; and,
Fig. 8 is a table of logical operations employed in the present invention.
DETAILED DESCRIPTION OF A PREFERRED
EMBODIMENT OF THE INVENTION
[0026] In the illustrated embodiment, there is provided a clock generator 31 for generating a display timing clock, and there is also provided a counter 32 having a column counter, a line counter and a row counter for generating a CRT screen display timing and a VRAM address in accordance with the display timing clock.
[0027] A data bus 41 from CPU 1 is connected via a buffer 42 to a register data bus 43. The number of registers included in Display Control Circuit 3 to be accessed by CPUl is held by a register pointer/counter 44 and the outputs of this register pointer/counter 44 are decoded by a register selector decoder 45, so that the respective registers can be specified. This register pointer/counter 44 has a count-up function in addition to a register function. Namely, when a parameter is set for each register, Register Pointer/Counter 44 counts up 1 after completion of each setting. Therefore, it can specify the registers one by one automatically and successively.
[0028] Also, the command information from CPU 1 is held by a command register 46, and a video CPU 47 is able to perform processings on the display data in accordance with the commands from CPU 1. Status from Video CPU 47 to CPU 1 is to be held by an SR register 48. When CPU 1 specifies the physical address of VRAM 4 to access VRAM 4, the VRAM address is held by a VRAM address register/counter 37. The write data to VRAM 4 and the read data from VRAM 4 are held by a color code register 33.
[0030] First, there are included an SA register 71 for setting up the value of a start physical address of a source area S, an SW register 72 for holding the logical width SW of an operation table area, a DA register 73 for setting up the value of a start physical address of a destination area D, and a DW register 74 for holding the logical width DW of a display area.
[0031] Also, there are provided a base value selector 75 which selects either a value of SA Register 71 or a value of DA Register 73, and a variation value selector 76 which selects one of a value of SW Register 72, a value of DW Register 74, and a value of an NX counter 64.
[0032] Further, the output of Base Value Selector 75 is connected to cne of inputs of an adder 80 and the output of Varia- tion Value Selector 76 is connected via a 2'S complement operation circuit 81 to the other input of Adder 80, whereby a variation value with respect to a memory address base value is added or subtracted to complete a practical circuit.
[0033] 2'S Complement Operation Circuit 81 is controlled by the value of either a horizontal direction flag 60 or a vertical direction flag 62 and is operable in cooperation with Adder 8C to perform addition or subtraction depending on the direction of transfer of the data.
[0034] The above-mentioned SA, DA registers 71, 73 are respectively provided with not only a function to receive the data established by Register Data Bus 43 therefrom but also a function to load the data from VRAM Address Bus 36 therein.
[0035] Next, an NX register 61 is used to hold the number of the transfer data in a horizontal direction (an X coordinate direction), and an NY register 63 is dedicated to holding the number of the transfer data in a vertical direction (a Y coordinate direction). Horizontal Direction Flag 60 points out a positive direction (a right direction) when it is "O", while it indicates a negative direction (a left direction) when it is "1". Vertical Direction Flag 62 points out a positive direction (a downward direction) when it is "O", while it indicates a negative direction (an upward direction) when it is "I".
[0036] The above-mentioned VRAM address bus 36, which is included in Display Control Circuit 3, is connected via a buffer 55 to an address line 56 of VRAM 4. A VRAM data bus 35 also in Display Control Circuit 3 is connected via a buffer 53 to a VRAM data line 54.
[0037] An S register 34 is used to hold the read data from the source area S, while a D register 52 is dedicated to holding the read data from the destination area D. An ALU (arithmetic and logic unit) 51 is adapted to peform logical operations, such as IMP, AND, OR, EOR, NOT operations, on the outputs of S Register 34, Color Code Register 34 and D Register 52 in accordance with the control from Video CPU47.
[0038] The foregoing components constitute the characteristics of the invention, although other components are still present in Display Control Circuit 3. However, such components as not necessary in explaining the operation of the invention are not described in this specification.
[0040] The operation of Display Control Circuit 3 will be discussed here by taking as an example the transfer of a block data using the X, Y coordinates in case where the logical transverse widths of the source area S and destination area D are different from each other.
[0041] It is necessary for CPU 1 to have previously set information necessary for transfer of the block data in the respective registers. When accessing each of the registers, CPU1 first sets the register number of a register to be accessed in Register Pointer/Counter 44, and thereafter performs its write operations on a series of data.
[0042] When such block data as shown in Fig. 3 is to be transferred, a physical address SA at a start point of the source area S is set in SA Register 71 and a physical address DA at a start point of the destination area D is set in DA Register 73. Here, SA Register 71 is composed of SAL (register #30), SAM (register #31) and SAH (register #32), while DA Register 73 is composed of DAL (register #35), DAM (register #36) and DAH (register #37).
[0043] In other words, CPUl sets 6-byte parameters regarding the physical addresses SA, DA at the start points of transfer, that is, at the respective start points of the source area S and the destination area D.
[0044] At the same time, the source-side area width SW is set in SW Register 72 and the destination-side area width DW is set in DW Register 74. Here, SW Register 72 is composed of SWL (register #33) and SWH (register #34), while DW Register 74 is composed of DWL (register #38) and DWH (register #39).
[0045] Now, Fig. 5 illustrates the contents of the registers #30 - 39, and Fig. 6 illustrates the contents of the registers #40 - 46.
[0046] Then, the number of the data to be transferred in a horizontal direction (an X coordinate direction), NX, is set in NX Register 61 and the number of the data to be transferred in a vertical direction (a Y coordinate direction), NY, is set in NY Register 63. NX Register 61 is composed of NXL (register #40) and NXH (register #41) and NY Register 63 is composed of NYL (register #42) and NYH (register #43).
[0047] Since the block data to be transferred is in the positive direction with respect to both of the X, Y directions when viewed from the start point SA, "0" is set in both Direction X Flag 60 and Direction Y Flag 62. Direction X Flag 60 corresponds to the bit 2 of an argument register ARGR (register #45), while Direction Y Flag 62 corresponds to the bit 3 of an argument register ARGR (register #45).
[0048] The above-mentioned setting operations complete the setting of parameters necessary to transfer the block data. These parameter settings are performed successively from Register #30 to Register #45. First, "30" is set in the register pointer/counter 44. Then, simply by writing the parameter data successively, the associated registers can be set sequentially. Thereafter, Register Pointer/Counter 44 points out #46 and waits for the setting of a command code.
[0049] Fig. 7 illustrates a table of command codes. In this figure, "VDC" stands for the display control circuit 3.
[0050] Fig. 8 illustrates a table of logical operations. In this figure, SC designates a source color code, while DC represents a destination color code.
[0051] CPU1 creates a command code such as "10010000" in accordance with the above-mentioned command codes and logical operation codes, and then sets it in Command Register 46 (register #46).
[0052] The higher 4 bits of the above-mentioned command code are a command to transfer a block data within VRAM 4 when the source area S and the destination area D are both present within VRAM4. The lower 4 bits of the same command code are a logical operation code and then "0000" is a code indicating that the source color code data as it is provides the destination color code data.
[0053] On receiving a command code from CPU1, Video CPU 47 sets the command executing (CE) of the bit 7 of SR Register 48 and initiates an executing processing of the command.
[0054] We, first, describe a case where a color code data is read out from the source area S within VRAM 4.
[0055] The physical address SA at the above-mentioned start point is found by the following equation and is set: in SA Register 71:
, where SB expresses the base of the start point and (SX,SY) expresses the coordinates of the start point.
[0056] Next, under control of Video CPU47, Base Value Selector 75 is operated, SA Register 71 holding the physical address SA of the start point of the source area S is selected, and the physical address SA is forwarded to Adder 80. Similarly, Valuation Value Selector 76 is operated, NX Counter 64 is selected, and the value of NX Counter 64 is forwarded to Adder 80.
[0057] In this case, if the i-th source address is expressed as SA(i,O), then this source address SA(i,0) can be obtained by the following equation:
, where i is a value that can be increased from O up to (NX-1) or the value i of NX Counter is increased one by one for each 1 dot transfer, and when a line of transfers in the source area S have been completed, i becomes NX to clear NX Counter.
[0058] Then, the value of SA Register 71 is updated in the following manner. Namely, Base Value Selector 75 selects the value of SA Register 71, Variation Value Selector 76 selects the value of DW Register 74 and Adder 80 adds these values, and outputs them to VRAM Address Bus 36. Further, Video CPU 47 controls the added value so that it can be loaded into SA Register 71. Accordingly, the next source address SA (0, 1) can be obtained in the following equation:
[0059] Here again, NX Counter 64 is counted by 1 each time 1 dot is transferred, and, if its value is expressed as i, then the source address SA (i, 1) can be found from the following equation:
The value i in the equation (3) is identical with the above-mentioned i, and 1 in the equation (3) indicates that 1 line has been advanced in the source area S, which can be expressed generally by the following equation:
The value j in the above equation (4) can be found from the amount of displacement off from the coordinates of the start point in the vertical direction.
[0060] In other words, the address at the start point is found from the above equation (1); the following addresses in the first line can be respectively given by the equation (2); when all of the addresses present in the first line have been completely transferred, then NX Counter 64 is cleared; addresses stored in the second and its following lines are generally given by the equation (4); and, each time the transfer of each of the lines is completed, the value i is counted 1 and the execution is handed over to the lower or following line. The above processings are then repeated.
[0061] In accordance with the respective addresses obtained in the above manner, data is read out from the operation table area within VRAM 4. The read-out data is set via Data Line 54, Buffer 53 and VRAM Data Bus 35 into S Register 34.
[0062] On the other hand, the color code data that is held in S Register 34 and is read out from the source area side is outputted via ALU 51, VRAM Data Bus 35 and Buffer 53 onto VRAM Data Line 54 and is then written into the display area within VRAM4. Procedures for creating the write address in this case are similar to those for creating the address read out from the above-mentioned source area.
[0063] In other words, here, DA Register 73 is used instead of SA Register 71, DW Register 74 is employed in place of SW Register 72, and a base DB and coordinates (DX, DY) are set up instead of the base SB of the start point of the source area S and the coordinates of the start point (DX, DY); however, the procedures for deducing the above-mentioned equation (4) from the above-mentioned equation (1) are the same as above.
[0064] In the foregoing operations, termination of both of reading of 1 dot from the source area S and writing of 1 dot into the destination area D completes the data transfer of 1 dot information. In the above discussion, since "0" is set in Direction X Flag 60 and Direction Y Flag 62, in horizontal-direction and vertical-direction processings, Complement 2'S Operation Circuit 81 is requested to perform no operation and an addition is executed in Adder 80.
[0065] Accordingly, on completion of transfer of the 1 dot information, Video CPU 47 counts up NX Counter 64. And, when all of the information contained in a line is completely transferred, NY Counter 65 is counted up by Video CPU47. If "1" is set in Direction X Flag 60 and Direction Y Flag 62, then in the horizontal-/vertical-direction processings 2'S Complement Operation Circuit 81 is requested to execute a complement operation and the resultant values are added in Adder 80, that is, a subtraction is executed.
[0066] For each transfer of the 1 dot information, the contents of NX Counter 64 and NX Register 61 are compared by Comparison Circuit 66, and, if they are not identical with each other, then the data transfer can be repeated in a procedure similar to the above-mentioned one. When the contents of NX Register 61 and NX Counter 64 are identical, then NX Counter 64 is to be cleared.
[0067] When the contents of NX Register 61 and NX Counter 64 are identical with each other and when the contents of NY Register 63 and NY Counter 65 are compared by Comarison Circuit 67 and found identical with each other, then a total of (NX X NY) pieces of block data have been transferred, where NX expresses the number of the X coordinate-direction block data and NY expresses the number of the Y coordinate-direction block data.
[0068] On detecting the coincidence of the contents of NX Register 61 with NX Counter 64 and the coincidence of the contents of NY Register 63 with NY Counter 65, Video CPU 47 decides that the block data transfer has been completed, clears the command executing (CE) bit of SR Register 48 and notifies CPU 1 of the completion of the block data transfer.
[0069] Although in the above description the command code was set in Command Register 46 as "10010000", if the lower 4 bits L03 - LOO are used to specify the logical operations illustrated in Fig. 8, then ALU 51 can function to execute the logical operations between S Register 34 and D Register 52.
[0070] In the above-mentioned description, although the block data transfer employing the X, Y coordinates within VRAM 4 was referred to, block data transfer from CPU 1 to VRAM 4, from VRAM 4 to CPU 1, and from Display Control Circuit 3 to VRAM 4 can also be executed in a similar manner to the above. Accordingly, such block data transfer will be discussed hereinbelow.
[0072] CPU 1 to VRAM 4, that is, when the command codes CM 3 - CM O are "1011" :
In this case, the source is CPU1, SA Register 71, SW Register 72 and S Register 34 are not used, but Color Code
[0074] Specifically, when CPU 1 sets a block of data to be transferred in Color Code Register 33, then Video CPU 47 writes the block data to be transferred in Color Code Register 33 into VRAM 4 in accordance with DA Register 73 and DW Register 74. After then, Video CPU 47 sets the transfer ready (TR) bit of SR Register 48 and notifies CPU 1 that the transfer of 1 piece of block data is completed and that the next block data can be accepted.
[0075] On confirming that the TR bit is "1", CPU1 sets the next transfer data in Color Code Register 33. This resets the TR bit to return to its original status. Other operations to be performed in this case are similar to those mentioned above in the case when the block data within VRAM 4 is transferred.
[0076] (2) When the block data is to be transferred from VRAM 4 to CPU 1, that is, when the command codes CM3 - CMO are "1010" :
[0077] In this instance, since the destination is CPU1, DA Register 73, DW Register 74 and S Register 34 are not used, but Color Code Register 33 is used instead of them.
[0078] Video CPU 47 reads out the transfer data from VRAM4 in accordance with SA Register 71 and SW Register 72, sets it in Color Code Register 33, and also sets the TR bit of SR Register 48 for " 1 ". CPU 1 checks the status of the TR bit and, if it is found "1", then it reads out a piece of block data from Color Code Register 33. This resets the status of the TR bit to return to its original status. Other operations required in this case are similar to those mentioned above in the case in which the block data within VRAP 4 is transferred.
[0080] Display Control Circuit3 to VRAM 4, that is, when command codes CM 3 - CM 0 are "1000" :
In this case, the data written into Color Code Register 33 is transferred to the destination area of VRAM 4. This way is effective in writing the same data. The procedure necessary in this case is similar to those in the above-mentioned transfer of the block data from CPU 1 to VRAM 4. However, CPU 1 needs writing the block data into Color Code Register'33 only once, while the transfer of the block data is executed under control of Video CPU47.
[0081] Although the foregoing description has been made on condition that the color code or color data is to be treated, the invention can also apply to a monochromatic system and in this case the above-mentioned color code or color data can be replaced with the byte data.
[0082] The present invention can be effectively used to perform a display control operation for not only the color CRT but also other display units such as a monochromatic CRT, LCD, plasma, EL and the like.
[0083] As disclosed hereinbefore, according to the invention, since even when the logical transverse width of the destination area is different from that of the source area most of the display operations to be processed by the software can be processed by the hardware in terms of time, the display memory access can be speeded up with smaller amounts of the necessary hardware increased for this purpose. The invention is also effectively used in a system in which a display memory is not separated from a main memory. Further, it is quite clear that the above-mentioned effect of the invention can also be applied to data transfer in the main memory.
1. An inter-logical-area data transfer control system for a memory unit (4) and comprising
display plane logic comprising:
means (7) for specifying a transfer start point of source area (S);
means (73) for specifying a transfer start point of a destination area (D) ;
means (61) for holding amounts of data to be transferred in a horizontal direction;
means (63) for holding amounts of data to be transferred in a vertical direction; and,
means (72, 74) for providing the logical transverse width of said source area (S) and the logical transverse width of said destination area (D) separately, characterized in that a plurality of data of said source area specified by said means are read out from said memory unit (4) and are sequentially written into said destination area (D) so as to achieve transfer of said data between said source and destination areas (S, D).
2. An inter-logical-area data transfer control system as defined in claim 1, characterized
in that said'memory unit is a display memory (4).
3. An inter-logical-area data transfer control system as defined in claim 1, characterized
in that said source area (S) or said destination area (D) is a main memory via a single
data register (34, 52).
4. An inter-logical-area data transfer control system as defined in claim 1, characterized
in that said source area is a data register (52) included in said data transfer control
system.
5. An inter-logical-area data transfer control system as defined in claim 1, characterized
in that a register pointer (44) for setting up command parameters is provided with
a count function and is capable of successive settings.
6. An inter-logical-area data transfer control system as defined in claim 1, characterized
in that there is provided means (60, 62) for holding each of horizontal and vertical
transfer directions of transfer points, and that said transfer directions comprise
directions in which, when said destination and source areas are superposed on each
other, said data is to be transferred in the order that said data within said source
area is not rewritten before the transfer of said data.
7. An inter-logical-area data transfer control system as defined in claim 1, characterized
in that said inter-area data transfer is performed by means of logical operation means'(51)
which logically operates on said data of said source area (S) and said data of said
destination area (D).
8. An inter-logical-area data transfer control system for a memory unit comprising
display plane logic, comprising:
means (71) for specifying a transfer start point of a source area (8);
means (73) for specifying a transfer start point of a destination area (D);
means (62) for holding amounts of data to be transferred in a horizontal direction; and,
means (63) for holding amounts of data to be transferred in a vertical direction, characterized in that a plurality of data of said source area (S) specified by said means are read out of said memory unit (4) and are sequentially written into said destination area (D) so as to achieve inter-area data transfer.