JPH0570171B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a printer buffer connected between a personal computer and a printer, and in particular performs DMA transfer of data and uses software commands during DMA transfer. The present invention relates to a printer buffer in which printer designation, data clearing, number of copies, etc. can be designated from the personal computer side.

<Prior Art> Printer buffers that buffer print data from a personal computer and output it to a printer generally employ software transfer that involves a CPU. For this reason, there was a problem in that it was difficult to transfer large amounts of data such as graphic data to the buffer memory at high speed.

<Problems to be Solved by the Invention> For this reason, printer buffers have been developed that transfer data directly to the buffer memory via DMA without the intervention of the CPU. is possible, but since the CPU is not involved in data transfer,
There was an issue in which various print-related commands could not be issued from the personal computer side.

That is, for example, when selecting one of multiple printers connected to a printer buffer, when specifying printer priority, when canceling data once transferred from a personal computer, etc. In some cases, it may be desirable to equip a printer buffer with a printer buffer, but in order to do so, the printer buffer itself must be equipped with a large number of operation switches, and in addition to the keyboard of a personal computer, the operator must There were problems such as poor operability as it was necessary to also operate the buffer operation switch.

The present invention was made to solve the above-mentioned problems, and it is possible to perform DMA transfer and to
Interrupt the transfer using a software command,
An object of the present invention is to provide a printer buffer that can perform various functional operations.

<Means for Solving the Problems> In order to achieve the above object, the printer buffer of the present invention, as shown in the block diagram of FIG. DMA the data to the buffer memory 12
In a printer buffer having a DMA circuit 14 for transfer, a register 1 stores data in a header portion of a predetermined software command.
8, a detection means 6 which compares the data on the input data bus and the data in the register 18, and detects the header part of the software command from within the input data based on the coincidence of both data; a transfer control means 7 that stops data input to the data input circuit and interrupts DMA transfer when a header portion of a software command is detected;
When the detection means 6 detects the header part of the software command, the command analysis means 8 takes in the software command data on the data bus, analyzes and recognizes the command, and the command analysis means 8 recognizes the software command. and functional operation control means 9 for controlling the functional operation indicated by the command to be executed when the command is executed.

<Operation> Operators of personal computers, etc.
When outputting print data, a predetermined software command is sent to the printer buffer through the same communication line as that used for outputting the print data. In printer buffer, DMA of input data
During the transfer, the detection means 6 compares the input data on the data bus with the data in the register 18, and detects the header portion of the software command from the input data based on a match between the two data.

When this detection means 6 detects the header part of the software command, the transfer control means 7 stops the data input of the data input circuit and
The transfer is interrupted, and the command analysis means 8 takes in the software command data on the data bus, analyzes and recognizes the command.

When the command analysis means 8 recognizes the software command, the function control means 9 controls the printer buffer to execute the functional operation indicated by the command, such as selection of an output port (printer), Functional operations such as switching, canceling input data, setting printer priority, and specifying the number of copies are executed by software commands from the personal computer.

<Example> Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 2 shows a block diagram of the printer buffer. This printer buffer is configured to buffer data sent from a parallel interface such as a personal computer and send it to the printer.

Reference numeral 11 denotes a data input circuit, which has a parallel port for inputting, for example, an 8-bit data signal sent from the outside, and is composed of a handshake type parallel interface. A buffer memory 12 temporarily stores print data sent from a personal computer or the like.

Reference numeral 13 denotes a data output circuit composed of a handshake type parallel interface, which outputs data read from the buffer memory 12 in parallel. This data output circuit 13 is provided with a plurality of output ports, and a plurality of printers are connected to each output port.

14 is a DMA (direct memory access) circuit that directly transfers data between the data input circuit 11 and the buffer memory 12, and when a DMA request is generated and a permission signal is input, it outputs the address to be transferred to the bus. The buffer memory 12 is configured to output a write signal to the buffer memory 12 to control data transfer.

The above data input circuit 11, buffer memory 1
2. Data output circuit 13 and DMA circuit 14
are interconnected via a data bus 20.

15 is a CPU that executes various processes associated with data buffering, especially when a software command is input during input data transfer.
A program that interrupts DMA transfer, analyzes the command, and executes the operation according to the command is stored in the built-in ROM in advance.

Functions operated by software commands include, for example, selecting an output port in the data output circuit 13, that is, a printer to which data is sent, canceling data, setting the priority of an output port, that is, a printer connected thereto, and controlling the printer. There are settings such as the number of copies, and these software commands are, for example, @BFOUT1;
It can be predetermined as @BFCLR1; @BFFIX1; @BFCPY2; etc.

Reference numeral 16 denotes a data reading circuit connected to the data bus 20, which is composed of, for example, a 3-state buffer circuit, and reads the data on the data bus, that is, command data, and sends it to the CPU 15 when a header portion of a software command is detected.

A comparison circuit 17 is connected to the data bus 20, and is composed of, for example, an 8-bit comparator. “@BF”)
Compare. If the data match, it is assumed that a software command has arrived on the data bus, and a command detection signal is output to the data input circuit 11 and the CPU 15.

An interrupt controller 19 outputs an interrupt signal to the CPU 15 when data is input to the data input circuit 11 or when a software command is detected.

Next, the operation of the printer buffer will be explained with reference to the flowchart shown in FIG.

Print data is output from the personal computer, and the first data signal is sent to data input circuit 1.
1, from the interrupt controller 19
An interrupt signal is output to the CPU 15, which causes
The CPU 15 enters the process shown in FIG.

When entering this process, the CPU 15 first sends an initial setting signal to the DMA circuit 14 in step 100.
Initial values such as the transfer address and transfer word length are set in the register of the DMA circuit 14.

Next, in step 110, the CPU 15 sends the data of the header part "@BF" of the software command to the register 18, and stores it there.

Then, in step 120, the CPU 15 outputs a DMA transfer permission signal to the DMA circuit 14, thereby starting the DMA transfer. Print data sent from a personal computer is directly transferred from a data input circuit 11 to a buffer memory 12, and is written into the memory at high speed by an address signal and a write signal generated from a DMA circuit 14.

Meanwhile, the CPU 15 waits for an interrupt at step 130, but while the DMA transfer is being performed, the comparator circuit 17 takes in the data on the data bus 20 and reads the header of the software command set in the register 18. The configuration data of the part is compared with the data on the data bus, and if they do not match, the DMA transfer continues.

On the other hand, when outputting print data, the personal computer operator selects the printer to which the data will be output, cancels the data, sets the printer's priority, or sets the number of copies for the printer, etc., as described above. If desired, a predetermined software command as described above is inserted at the beginning of the data or in the middle of the data, and the data is output.

And that software command, e.g.
When “@BFOUT1;” appears on the data bus,
The comparison circuit 17 compares the data with the data stored in the header section "@BF" register 18 and finds a match. Therefore, a match signal is sent to the interrupt controller 19 and the data input circuit 11, which causes the data input circuit 11 to stop the data input process, and the interrupt controller 19 to the CPU 15.
Outputs an interrupt signal to generate an interrupt.

At this time, step 130 to step 140 in FIG.
Then, the CPU 15 outputs a transfer stop signal to the DMA circuit 14 to interrupt the transfer.

Then, in step 150, the CPU 15 reads the data on the data bus at that time, that is, the character string data of the software command, via the data reading circuit 16, and analyzes the command. As a result of the analysis, if the command is recognized as “@BFOUT1;”, in step 160, the CPU 15
performs control processing such as switching the output port of the data output circuit 13 to 1.

After that, the process returns to step 120 again, and the CPU 15
A permission signal is sent to the DMA circuit 14, thereby restarting the DMA transfer.

Note that, for example, if a software command sent from a personal computer is “@BFOUT1/
2'', the CPU 15 allows the output port (printer) in the data output circuit 13 to be arbitrarily selected as output port 1 or output port 2, depending on the usage state of the output port.

Also, for example, if a software command sent from a personal computer is “@BFCLR1;”
, the CPU 15 uses buffer memory 1
2 to erase the data in the buffer memory (data to be output to the output port 1 or printer 1).

Further, for example, if the software command sent from the personal computer is "@BFFIX1", the CPU 15 sends the data output circuit 13
Output port 1
Fixed to.

Further, if the software command is "@BFCPY2;", the CPU 15 causes the data output circuit 13 to output a command signal indicating the number of print sheets, each two, to the printer.

In this way, software commands can be used to switch output ports, erase data sent by mistake, and specify the number of copies, so the operator does not have to go to the printer buffer and operate it. Also, printing-related specifications can be easily made by simply operating the keyboard at the personal computer.

<Effects of the Invention> As explained above, according to the printer buffer of the present invention, since it is configured as above, the CPU
Even with a printer buffer that performs DMA transfer without intervening a It is possible to specify the priority of files, erase sent data, specify the number of copies, etc. Therefore, the operator does not have to go to the printer buffer and operate it, just by operating the keyboard at the personal computer.
Various specified operations related to printing can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of the present invention, and FIG. 2 is a block diagram of a printer buffer showing an embodiment of the present invention.
FIG. 3 is a flowchart showing the operation. 6...Detection means, 7...Transfer control means, 8...Command analysis means, 9...Function operation control means, 11...Data input circuit, 12...Buffer memory, 14...
DMA circuit, 18... register.

Claims (1)

[Scope of Claims] 1. In a printer buffer having a DMA circuit that DMA-transfers data on a data bus input through a data input circuit to a buffer memory, data in a header portion of a predetermined software command a register for storing the input data, a detection means for comparing the input data on the data bus with the data in the register, and detecting the header part of the software command from the input data based on a match between the two data; transfer control means for stopping data input to the data input circuit and interrupting DMA transfer when the means detects a header portion of a software command; a command analysis means that takes in the above software command data and analyzes and recognizes the command; and a functional operation that controls the command analysis means to execute the functional operation indicated by the command when the command analysis means recognizes the software command. A printer buffer comprising: a control means;