JPS63233843A - Bit map memory control device - Google Patents

Abstract

PURPOSE:To improve a high speed of image drawing and printout by providing a constitution in which data for image drawing of an area left behind without being output to a laser beam printer is erased before writing the following data for image drawing. CONSTITUTION:Prior to writing data for image drawing into a bit map memory module 3, the data for image drawing left behind without being output is read by an I/F control module 5 through a DMA bus 9. Then the data for image drawing which is read in the above manner is subjected to a dummy DMA transfer action without being transferred to a laser beam printer 4, i.e. transferring to a data erasure circuit other than the laser beam printer 4. Thus data for image drawing which remains in the bit map memory module 3 is erased. As a result, a device capable of further speeding up the writing and printout processes can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a bitmap memory control device used to control pixels that create images in Kanji printers, CRT controllers, and the like.

[Conventional technology]

FIG. 4 is a block connection diagram of a conventional bitmap memory control device disclosed in, for example, Japanese Unexamined Patent Publication No. 60-183627. In the figure, 1 is a host, and 2 receives a data signal from the host 1. 3 is a host interface control module; 3 is an nXm matrix bitmap memory module for storing drawing data; 4 is a laser beam printer; 5 is an interface for transferring data to the laser beam printer 4 (hereinafter referred to as ■
6 is a read-only memory (hereinafter referred to as /F) control module that stores processing programs, etc.
Random Access Memory (hereinafter referred to as ROM), Random Access Memory (hereinafter referred to as
7 is a central processing unit (hereinafter referred to as CPU) module that controls processing programs, 8 is a common bus, and 9 is a direct memory access (hereinafter referred to as DMA) bus.

5 is a signal line configuration diagram for DMA transfer between the bitmap memory module 3 and I/F control module 5 in FIG. 4, and FIG. 7 is a circuit diagram showing a peripheral circuit per bit of the dynamic RAM 12 in the bitmap memory module 3, and FIG. 7 is an operation time chart of the dynamic RAM 12 in the bitmap memory module 3 in FIG. 4.

Next, the operation will be explained. The drawing data in the bitmap memory module 3 written by the CPU module 7 in FIG.
DMA data is transferred to the F control module 5 via the DMA bus 9.

The 1/F control module 5 controls the output to the laser beam printer 4, and at the same time performs the above-mentioned DMA data transfer operation and transfers the transferred data from parallel to serial to the laser beam printer 4. The three operations of converting and outputting serial data in synchronization with a synchronous clock are repeatedly executed.

Figure 5! /F control module 5 writes an address and a read (R) to bitmap memory module 3 before data transfer to laser beam printer 4.
EAD) signal.

Next, the operation will be explained. The drawing data in the bitmap memory module 3 written by the CPU module 7 in FIG.
DMA data is transferred to the F control module 5 via the DMA bus 9.

The I/F control module 5 controls the output to the laser beam printer 4, and at the same time performs the above-mentioned DMA data transfer operation and parallel-to-serial conversion of the transferred data to the laser beam printer 4. and three operations of outputting serial data in synchronization with a synchronous clock are repeatedly executed.

The I/F control module 5 in FIG. 5 writes an address and a read (R
EAD) signal.

Upon receiving the read signal, the bitmap memory module 3 composed of a large-capacity dynamic RAM 12 first receives a row address strobe (hereinafter referred to as RAS) signal and then a column address strobe (hereinafter referred to as RAS) signal. , CAS) signal is generated, ! The drawing data specified by the bit address bus is
Send to n-bit data bus. Furthermore, a strobe (hereinafter referred to as STB) indicates that the transmitted data is stable.
Notify with a signal.

The I/F control module 5 that received the STB signal latches the contents on the n-bit data bus,
Parallel-to-serial conversion is performed using the synchronized clock from the laser beam printer 4, and the data is sent to the laser beam printer 4 as serial data.

At the same time, by sending a write signal back to the bitmap memory module 3, erase data can be written to the same address specified by the 2-bit address bus. In the example of FIG. 6, "1"' is written by the pull-up resistor R. Therefore, by continuously executing the DMA data transfer operation from the bitmap memory module 3 including the read operation and write (that is, erase) operation, the drawing data at the same address can be output while the drawing data is being output. Delete all data.

[Problem that the invention seeks to solve]

Since the conventional bitmap memory control device is configured as described above, the bitmap memory module 3
If the area position of the drawing data above is not the same as the area position of the drawing data transferred and output to the laser beam printer, the drawing data of the area that was not output will remain as garbage, and this garbage To avoid this, the entire bitmap memory module must be erased again before the next drawing, which takes time for the erase operation and slows down the next drawing and printout. There were problems such as:

This invention was made to solve the above-mentioned problems, and it is possible to minimize the time for erasing operations, and to greatly improve the speed of drawing and print output. The purpose of this invention is to obtain a bitmap memory control device that can perform the following steps.

[Means for solving problems]

A bitmap memory control device according to the present invention provides an output position for storing an area position output to a laser beam printer by an I/F control module among area positions of drawing data on a bitmap memory module. A storage device is provided, and based on the area position which is the stored data, the drawing data of the area remaining without being output to the laser beam printer is erased before writing the next drawing data. It is something.

[Operation] The I/F control module according to the present invention transfers some of the drawing data left by the DMA transfer operation from the bitmap memory module, based on the storage data of the area position stored by the output position storage device. , erase by dummy DMA data transfer operation.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, numerals 1 to 9 are exactly the same as those shown in FIG. 3, and redundant explanation thereof will be omitted. 10 indicates the laser beam on the bitmap memory module 3.
This is an output position storage device that stores the area position of drawing data sent to the printer 4. This output position storage device 1
0 is also connected to the common bus 8. Further, FIG. 2 is an explanatory diagram for explaining the processing status of the drawing data, and FIG. 3 is a flowchart showing the procedure for erasing the drawing data of the unreleased Canilia.

Next, the operation will be explained with reference to FIGS. 2 and 3. In this embodiment as well, writing data for drawing into the bitmap memory module 3 and sending data for drawing to the laser beam printer 4 are as follows.
This is exactly the same as the conventional method. In this example, the CPU
The module 7 writes drawing data to the bitmap memory module 3 through the common bus 8 (step 1ST). At this time, the bitmap memory module 3 is written as shown in FIG. The drawing data is written as shown in FIG.
Then, data is transferred via the DMA bus 9. At this time, the output position storage device 10 is connected to the laser beam printer 4 via its IF control module 5.
The area position of the drawing data to be output, that is, the output position 11 shown in FIG. 2(b) is stored. Next, I/
The F control module 5 converts the drawing data from parallel to serial, synchronizes it with the periodic clock, outputs it to the laser beam printer 4, and repeats this operation (step 2ST). In FIG. 2(C), among the drawing data on the bitmap memory module 3, the white part on the right side from the output position 11 that is not shaded is
Indicates that it is the output drawing data part.

Next, before writing the next drawing data to the bitmap memory module 3, start from the beginning of this bitmap memory module 3 to the above area! (Output position) up to 11, that is, the remaining drawing data that has not been output, is
/F control module 5 through the DMA bus 9. The read drawing data is then erased without being transferred to the laser beam printer 4. Here, the drawing data remaining after the DMA data transfer from the bitmap memory module 3 is not transferred to the laser beam printer 4 as described above,
The drawing data remaining in the bitmap memory module 3 is erased by performing a dummy DMA transfer operation, that is, by sending it to a data erasing circuit other than the laser beam printer 4 (step 3ST).
. FIG. 2(C) shows the contents of the bitmap memory module 3 in this erased state.

Note that in the above embodiment, the drawing data bitmap/
The output position 11 in the memory module 3 is determined as the position from the beginning with the left end of the bitmap memory module 3 as the beginning, but the beginning is set to the right end, top end, or bottom end of the bitmap memory module. However, the same effect as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the output position storage device stores the area position of the drawing data sent to the laser beam printer in the bitmap memory module, and based on this area position, the laser beam Since the drawing data in the area position remaining without being sent to the beam printer is erased by dummy transfer etc., it is possible to minimize the time required for erasing before writing the next drawing data. can,
As a result, there is an effect that the writing and printing operations described above can be further speeded up.

[Brief explanation of drawings]

FIG. 1 is a block connection diagram showing a bitmap memory control device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the processing status of drawing data on the bitmap memory module, and FIG. 3 4 is a block connection diagram showing a conventional bitmap memory control device, FIG. 5 is an explanatory diagram of a DMA transfer signal, and FIG. 6 is a circuit diagram around the dynamic RAM. 7th
The figure is a time chart of dynamic RAM operation signals. 3 is a bitmap memory module, 4 is a laser beam printer, and 5 is an interface control.
7 is a central processing unit module, and 10 is an output position storage device. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Figure 4 Page 5 116 Figure 7 CAS '' Rabet

Claims (2)

[Claims] (1) The bitmap and
Directly transfers drawing data written to the memory module to the interface control module.
This interface control module converts the drawing data from parallel to serial and outputs it to the laser beam printer based on the synchronized clock from the laser beam printer, and also transfers the memory access to the bitmap memory. A bitmap configured to write erase data at the same location as the drawing data addressed to the module.
The memory control device is provided with an output position storage device that stores the position of an area to be output to the laser beam printer among the areas of drawing data in the bitmap memory module, and based on this stored data, there is an output position storage device that stores the position of the area to be output to the laser beam printer, and based on this storage data, the area of the drawing data of the bitmap memory module is stored. A bitmap memory control device characterized in that drawing data in an area is erased before writing the next drawing data. (2) The bitmap image recited in claim 1, wherein the area drawing data remaining in the bitmap memory module without being output to the laser beam printer is erased by a dummy transfer operation. Memory controller.