JPH04140162A - Printer - Google Patents

Abstract

PURPOSE:To enable the high-speed processing of print data by using a dual port memory as page memory. CONSTITUTION:One page of print data is put together and bit map-developed on the RAM port 22 in a dual port memory. Then, when MPU21 conducts a read transfer cycle to the dual port memory 22 with RA=m-address and CA(column address)=0-address, data for the first line is transferred in a moment to SAM port. Subsequently, when a serial clock 29 is sent out from a controller part 24 to the SAM port, the clock is inputted not only to FIFO buffer 25 but also to a counter part 23 so that the number of read data from the SAM port is reckoned. Then, interrupt is applied to a microprocessor 21 by the count end signal 32 of the number to inform that all data of the SAM port have been read out. In response to this, the microprocessor 21 renews a row address by one(RA=m+1) to conduct a read transfer cycle to transfer data in the following line to the SAM port.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a printing device, and particularly to a so-called page printer that prints on paper based on print data sent from a host computer or other host device. It is something.

(b) Prior Art Generally, a printer that prints based on data sent from a host computer is constructed as shown in FIG.

As shown in Figure 5, the data is temporarily stored in the system RAM.
(4), and according to its contents, for example, in the case of a character code, the corresponding font data is retrieved from the font memory (5), and normally the DR
A bitmap is developed on the vegetable memory (6) composed of AM. Further, the bitmap data is transferred to the video interface (7), where it is converted into a serial video signal and sent to the printer engine (8). Then, the printer engine (8) performs rask scanning according to the video signal and prints on the paper.

Traditionally, the transfer of bitmap data from the page memory (6) to the video interface (7) is accomplished via the system bus using a microprocessor (2) or, if speed is required, direct memory access (DMA) (not shown). (9) This was done through (1o).

However, this method naturally has a limit to its processing speed, and is not suitable for medium to high speed printers.

Therefore, as a means to perform faster processing, a bus managed by another microprocessor or a processor dedicated to drawing is provided in addition to the system bus, and the font memory (5) and page memo 1/video interface are placed on it. Accordingly, a system has been devised in which image processing such as bitmap development is performed in parallel with data processing (code analysis, etc.) from the host (for example, there is the PC-PR601 manufactured by NEC Corporation).

Another method is to provide a bus (11) for transferring the bitmap data to the video interface, and make the bus to the page memory (6) redundant. It has also been devised to increase the speed by developing the page data into a bitmap (see Japanese Patent Application Laid-Open No. 1547-1987 for details).

(c) Problems to be solved by the invention However, in the former case, since there is only one bus that can access the page memory, bitmap data transfer and drawing (bitmap expansion) cannot be performed at the same time, and there is a limit to speeding up. be.

In addition, even if the bus to the page memory is duplicated as in the latter case, the circuit becomes complicated, and the capacity per memory chip is increasing, so it is necessary to make the bitmap data transfer part and the drawing part coexist. Even when dividing page memory, bus separation can only be done on a chip-by-chip basis.
It has the disadvantage that it is very difficult to divide and manage it freely.

(d) Means for Solving the Problems The present invention has a page memory composed of a dual port memory consisting of a RAM port and a SAM port, and print information is accessed based on print data sent from a host device. means for expanding a bitmap onto the RAM port; means for transferring the expanded bitmap data from the RAM port to the SAM port by specifying a transfer start address; reading the data from the SAM port;
It is characterized by comprising means for converting the read data into serial data and sending it to the printer mechanism side.

(E) Function The present invention employs a dual port memory consisting of a RAM port and a SAM (serial access memory) port for the page memory.

Therefore, sending and drawing of bitmap data can be performed simultaneously without duplicating buses, and high-speed processing of print data becomes possible.

In addition, by providing a means to arbitrarily set the start address of the data to be sent from the page memory and the number of data to be sent from the SAM port, it is possible to freely divide the page memory or allocate memory for one page. Become so.

(F) Embodiment In an embodiment of the present invention, the configuration of the page memory and video interface periphery is shown in FIG. It is shown in Figure 2.

The explanation will be given below.

First, the print data sent from the host is stored in one page at a time in the RAM port of the dual port memory (
22) Expand the bitmap on top.

As shown in FIG. 2(a), if the number of scanning lines per page is N, the data is allocated to the page memory as shown in FIG. 2(b). In other words, RAM
Since the port is composed of DRAM, MPU (21
), from the beginning of the row specified by a certain row address (RA), for example, from the place specified by RA = address m, CA (column address) = address O, the first wood (IH)
, 2nd grain (2H), .

Then, in order to move on to the printing operation, work is started to send the bitmap data developed in the RAM boat to the printer engine side.

The procedure is to first perform a read transfer cycle to the dual port memory (22) with RA=m and CA=O (FIG. 3(C)). Then, the data of the first stake shown in Figure 3(b), that is, the IH specified by RA=m
The data up to the middle of 4H is instantaneously transferred to the SAM port as indicated by the arrow (33) in the figure. In the present invention, the data length is 16 bits wide and the column address of one memory chip is 9 bits (512).
Data of bits x 512 will be sent to the SAM port.

Next, when the controller unit (24) sends the serial clock (29) to the SAM port, 16-bit wide parallel data (30) is sequentially read out from CA=O according to the clock and input to the FIFO buffer (25). be done. Figure 3 (
2) and (3). A certain amount of data has been entered and the FI
When the FO buffer (25) becomes full, its signal (31
), in response to (4) in FIG. 3, the controller section (24) interrupts clock transmission. And the FIFO buffer (
When data is transferred from 25) to the engine side through the parallel-serial converter (26) and free space is created in the FIFO buffer (25), the FIFO is transferred from the SAM port again to the FIFO buffer (25).
A clock is generated to transfer data to the FO buffer (25).

This clock is also input to a counter section (23), so that the number of data read from the SAM port can be counted. Then, preset the count value (-number of equity data, in this case 512),
The count end signal (32) of that number causes an interrupt to the microprocessor (21) at (5) in FIG.
Notifies that all data in the M port has been read and is now empty.

In response to this, the microprocessor (21) advances the row address by one (RA-m+1), performs a read transfer cycle (Figure 3(d)), and transfers the next row of data to the SAM port. do. Then, parallel data is sent to the FIFO buffer (25) again, and by repeating these operations, the sending of one page's worth of bitmap data is completed.

Thus, the work of the microprocessor (21) during bitmap data transmission is only to perform read transfer cycles, and this is the only time the microprocessor (21) occupies the bus to the RAM port for data transmission. This time is shown in Figure 3(c), (
As is clear from d), the amount is very small. Therefore,
Most of the time can be devoted to data processing of the next page, for example, to a free memory space or to bitmap expansion to a portion of a page that has already been sent out.

Therefore, high-speed processing of print data and even high-speed printing are possible.

Further, by arbitrarily specifying a column address during a read transfer cycle, the transfer start address can be freely set, and by changing the preset value to the counter section, the number of data transfers per row can be arbitrarily set. Therefore 1
The memory allocation for one page or the method of dividing the memory (setting the number of divisions, its capacity, etc.) can be freely selected, making it possible to respond to various requests.

In addition, as shown in Figure 4, the dual port memory (22), which is page memory, the font memory (53), etc. are placed on another bus managed by the drawing processor (52), and drawing operations are performed on them. If the configuration is configured to perform dedicated operations, analysis of data from the host, bitmap expansion,
The three tasks of transmitting bitmap data can be performed simultaneously and in parallel, and further speeding up can be expected.

(G) Effects of the Invention As described above, in the present invention, by adopting a dual port memory as the page memory, high-speed processing of print data is possible, and data is transferred from the memory to the engine side. By arbitrarily setting the transfer start address and the number of data to be transferred, page memory allocation and division management can now be performed freely.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention. Figure 2 (a) is a schematic diagram showing the scanning lines of one page, Figure 2 (b) is a schematic diagram showing the memory allocation of the data (b), and Figure 3 is a schematic diagram showing the transmission sequence of bitmap data. FIG. FIG. 4 is a block diagram showing another embodiment of the present invention. FIG. 5 is a block diagram showing a conventional configuration. 21...Microprocessor, 22...Dual port memo 1c 23...Counter section, 24...Controller section, 25...FIF○ buffer, 26...Parallel-serial conversion section, 27... - Printer engine, 28... system bus. Figure 3 (3c\”%1wγ-7 So?==2?n3)5◇CC(E(?2XZ2￥lIm
2 = = =

Claims (1)

[Claims] (1) RAM port and serial access memory (hereinafter referred to as
It's called SAM. ) has a page memory constituted by a dual port memory consisting of ports, and print information is sent to the RA based on print data sent from a host device.
A means for developing a bitmap on the M port, a means for specifying the transfer start address of the developed bitmap data and transferring it from the RAM port to the SAM port, and a means for reading the data from the SAM port and serially serializing the read data. 1. A printing device comprising means for converting data into data and sending the converted data to a printer mechanism section.