JP3260862B2 - Parallel data transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel data transmission device for transmitting data from a computer to a printer, and more particularly, to a conventional strobe (synchronous clock) for transmission data using a Centronics interface. The present invention relates to a parallel data transmission device that realizes high-speed data transmission by mixing a corresponding component to transmit only data on a transmission side and simultaneously monitoring a clock and fetching data on a reception side.

[0002]

2. Description of the Related Art As a conventional parallel data transmission method, a Centronics interface used between a computer and a printer is generally used. This interface is a standard developed by Centronics Corporation in the United States for transmitting data from a computer to a printer in parallel (8-bit parallel). The Centronics interface includes an 8-bit parallel data line, a strobe signal indicating that data has been determined, a busy signal indicating that the printer (reception side) is operating, and an ack signal indicating that data can be received. It consists of a handshake line.

FIG. 8 is a timing chart showing general data transmission by the Centronics interface, and FIG. 9 is a flowchart showing a data transmission sequence. The busy signal is a positive logic control signal,
On the other hand, the strobe signal is a negative logic control signal. FIG.
In FIG. 9 and FIG. 9, the computer inputs a busy signal state from the input port (S901).
It is determined whether the printer is busy (S90).
2). If it is determined that the printer is not in the busy state, the transmission data is taken out and output to the parallel port (S903), and waits for the data set time (t1) (S904). Thereafter, the strobe is set (S90).
5), waiting for data lead time (t2) (S906)
After that, the strobe is released (S907), and waits for the data hold time (t3) (S908). afterwards,
It is determined whether or not there is transmission data (S909). When it is determined that there is transmission data, the process returns to step 901. On the other hand, when it is determined that there is no transmission data, this processing ends. If it is determined in step 902 that the printer is busy, the process returns to step 901.

Thus, the Centronics interface realizes asynchronous parallel data transmission. The data set time (t1) shown in FIG.
Data lead time (t2) and data hold time (t3) are at least 0.5 microsecond (μs)
ec).

Therefore, most of the general computer-based Centronics interface has a simple input / output port, and the computer-side sequence is entirely controlled by software as described with reference to FIGS. Was. Further, by using such a method, a conventional printer is a dot impact printer for a text database, and thus has satisfactory processing speed and the like. This is because the processing speed of the computer is far superior to the processing speed of the printer.

[0006]

However, in the conventional parallel data transmission system as described above, it has recently become difficult to cope with a high-speed laser printer which is particularly popular. In other words, laser printers have been improved in speed, and the data to be processed contains a lot of image data. As a result, a large amount of data is handled. Performance is required. As described above, when the speed of the printer is increased, the processing by software control on the computer side is restricted on the contrary, and the problem that it is difficult to follow the processing performance of the printer has been highlighted.

As a means for solving the above-mentioned problem, for example, a computer-based interface can be realized by a hardware-based control method using a well-known DMA (direct memory access) transfer process. However, this DMA transfer method has a problem that it requires expensive hardware change and cannot be applied to a conventional device having a centronics interface composed of simple input / output ports.

The present invention has been made in view of the above, and realizes high-speed data transmission between a computer and a printer only by software control using existing hardware, thereby improving economy and versatility of equipment. The purpose is to let them.

[0009]

The present invention SUMMARY OF], in order to achieve the above object, a plurality of bit sequences and one unit of data, and parallel output means for transmitting data in parallel for each said data unit, said parallel 1 transmitted by output means
The part of the unit data where the same data is adjacent is
Code to be converted into a code sequence composed of different data
An object of the present invention is to provide a parallel data transmission apparatus comprising: a conversion unit; and a transmission unit that transmits a code sequence obtained by converting a transmission data sequence by the coding unit to the parallel output unit.

Further, the parallel output means for a plurality of bit sequences and one unit of data, transmitting data in parallel for each said data unit, 1 transmitted by said parallel output means
The part of the unit data where the same data is adjacent is
Encoding means for converting the transmission data sequence into a continuous data pattern and converting it into a continuous length code to form a code sequence, while converting the transmission data sequence into a continuous data pattern; And a transmitting means for transmitting a code string obtained by converting the data to the parallel output means to the parallel output means.

[0011]

According to the parallel data transmission apparatus of the present invention, one unit transmitted by the parallel output means by the encoding means is provided.
Of adjacent data with the same data
In this case, the data is converted into a code string composed of different data, and the code string is output in parallel from the parallel output means via the transmission means to improve data transmission efficiency.

[0012] Further, a parallel output means is provided by the encoding means.
Data of one unit of data transmitted by
Adjacent parts are composed of different data
By converting the data into a code sequence and converting the transmission data sequence into a continuous length code when the data sequence is a continuous data pattern to generate a code sequence, and outputting the code sequence in parallel from a parallel output unit via a transmission unit, , To compress data and transmit large amounts of data at high speed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The gist of the present invention is to transmit only data on the computer side (transmission side) and to transmit data on the printer side (reception side) by mixing components corresponding to a conventional strobe (synchronous clock) into transmission data. The monitoring of the clock and the fetching of the data are simultaneously executed. Conventionally, data transmission was performed using strobes because it was necessary to notify the receiving side that transmission data was determined. For example, "1", "2", "2",
When four data "3" are transmitted, each data is transmitted to an output port and a strobe is generated. Here, if attention is paid only to the data, only “1”, “2”, and “3” are changed. Therefore, the transmitted data sequence is “1”, “2”, “3”, or “1”. , “2”, “2”, and “3” cannot be determined. The present invention focuses on this point, and utilizes the fact that, when transmitting a data sequence configured so that adjacent data is always different, it is possible to determine on the receiving side without generating a strobe for each data. Things.

Therefore, in the present embodiment, in order to realize the above-mentioned idea, hardware of a generally used Centronics interface is used and applied to data transmission between a computer and a printer. .

An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing a basic configuration of a parallel data transmission device according to the present invention, which is largely composed of a computer side (transmission side) and a printer side (reception side). In the figure, the computer side is 10
An encoder for converting the transmission message of No. 1 into code data so that adjacent data is always different;
A transmitter for simply outputting the code data from 01,
103 parallel output ports. On the printer side, 104 parallel input ports and 1
A receiving unit 05 detects a change point of the received data and buffers the code string, and a decoder 106 decodes the received code string into the original transmission message. In the present embodiment, the processes performed by the encoder 101 and the decoder 106 are separately configured as a transmission process and a reception process. However, these encoding / decoding processes are performed simultaneously when transmitting and receiving data. Is also good.

Next, the operation and the like of the parallel data transmission apparatus configured as described above will be described in detail by dividing the following items. (1) Data transmission procedure (2) Data reception procedure (3) Configuration of encoder and decoder (4) Encoding procedure (5) Encoding example (6) Decoding procedure (7) Decoding Example

(1) Procedure of Data Transmission FIG. 2 is a flowchart showing an example of the procedure of data transmission according to the present invention. In the figure, first, a transmission message sequence is encoded into a transmission code sequence by an encoder 101 (conversion process).
(S201), 1-byte data is extracted from the transmission code string and set in the parallel output port 103 (S2).
02). Further, after waiting for the data hold time (t4) (S203), it is determined whether or not the code string is completed (S204). As a result of the determination, when it is determined that the code string has been completed, this routine is terminated. On the other hand, when the transmission code string to be transmitted remains, the above-described step 20 is performed.
2, the same process is performed.

As described above, since the transmission sequence is simply a repetition of the operation of outputting data to the parallel output port 103, the data transmission performance can be used almost to the limit of the processing capability of the processor. In addition,
The waiting of the data hold time (t4) is executed to slightly adjust the timing in order to correspond to the processing capacity of the processor.
Since the same data is held in the parallel output port 103 during the processor processing time in steps (2) and (4), the data hold time (t4) may be zero if there is no restriction on hardware.

(2) Procedure of Data Reception FIG. 3 is a flowchart showing an example of the procedure of data reception according to the present invention. In the figure, first, the receiving unit 105 initializes the variable P holding the previous input data by setting it to −1 (S301), and inputs data from the parallel input port 104 (S302). Thereafter, it is determined whether or not DATA = P (S303). When it is determined that DATA = P, the process returns to step 302. on the other hand,
When it is determined that DATA = P is not satisfied, after waiting for the data setup time (t5) (S304), data is input from the parallel input port 104 (S30).
5), add data to the code string (S306). next,
Data is set in the variable P (S307), and it is determined whether or not the reception processing has been completed (S308). When it is determined that the reception processing has not been completed, the process returns to step 302, and when it is determined that the reception processing has been completed, the reception code string has been received. Is converted into a message string by the decoder 106 (S309), and this routine ends.

The reason why the data is again input from the parallel input port 104 in the steps 305 and 306 is because it is assumed that the data input in the step 302 is in an excessive state. That is, since there is a possibility that a plurality of bits may change, at the time of step 302, there is a possibility that all bits are input in a state where they have not changed. Therefore, the data setup time (t5) is a guaranteed period until all data bits are stabilized as parallel data. In this embodiment, the data setup time (t5) is set to 0.5 in the ordinary Centronics interface.
It was confirmed that microseconds (μsec) were sufficient.

(3) Configuration of Encoder and Decoder The encoder 101 is configured to generate a code such that adjacent data does not match in units of 1 byte (8 bits) because a centronics interface is used. . Although various means for satisfying such a condition can be considered, the following relationship must be satisfied as the gist of the present invention. That is, (encoding time + transmission time) <transmission time by the conventional transmission method.

Accordingly, in the present embodiment, the following method is employed to minimize the processing time. If adjacent data is different in the message sequence, the data in the same state is processed as a code. When adjacent data match, that is, when it is determined that the pattern is a continuous data pattern, a special pattern (hereinafter, referred to as a flag) to which the length of the continuous data is added is processed as a code. The flag is defined by a 3-byte data string as follows. Flags when data X continues for M bytes are (X), (X + 1), (X + M)
Expressed in 3 bytes. However, M is a value in the range of 2 to 255. Further, since this flag can be regarded as a run length code (run length code), when the continuous pattern is 4 bytes or more, an effect of compressing data can be expected. If a pattern that matches the format of the first two bytes of the flag occurs in the message sequence, processing is performed with the continuous data length M set to 0 in the flag pattern. That is, if the original data is a pattern of (X), (X + 1), it is encoded as (X), (X + 1), (X).

(4) Encoding Procedure FIG. 4 is a flowchart showing an encoding procedure according to the present invention. Here, the variable P is used to determine whether or not the transmission message is a continuous pattern and whether or not the transmission message matches the flag pattern. In FIG. 4, first, initialization is performed with a value that cannot occur in the received message sequence, that is, the variable P is initialized by setting −1 (S401). Is read (S402), and it is determined whether or not all the received messages have been completed (S403). At this time, if it is determined that all the received messages have been completed, this routine is terminated.
Further, it is determined whether or not M = P (S404). That is, it is determined whether or not the received message has a continuous pattern.

If it is determined in step 404 that a pattern matching the previous data P has occurred (M = P), a flag pattern (M + 1) is added to the code string assuming that the pattern is continuous data (S405). Next, since at least two bytes of continuous data have been detected at this time, a variable C for counting the number of continuous data is initialized to 2 (S406), and based on a repetition loop L (steps 407 to 411) described below. Count continuous data.

That is, data is read into the variable M from the received message sequence in byte units (S407), and it is determined whether or not all the received messages have been completed (S408).
At this time, when it is determined that there is a received message to be transmitted (not completed), it is further determined whether or not M = P (S409), and whether or not the received message is a continuous pattern is determined. . Next, it is determined whether the variable C for counting the continuous number is equal to or less than 255 (C <255) (S410), and the variable C for counting the continuous number is 2
If it is determined that it is 55 or less, 1 is further added to C (C + 1) (S411), and the process returns to step 407,
Execute the loop L repeatedly.

The conditions for exiting the repetition loop L are three cases: the end of the message, the mismatch of the data, and the limit on the continuous number generated due to the 8-bit data to be handled. That is, when it is determined in step 408 that the message has ended, when it is determined in step 409 that a pattern matching the previous data P has occurred (M = P), and when it is determined in step 410 that C> 255. It is. In this case, C is added to P (S4
12) Further, since the number of continuous data is set in C, the third byte (P + M) of the flag is added to the code string (S413). Then, at this point, the next message string has already been read into the variable M, so
3 and the above-described processing is executed.

On the other hand, if it is determined in step 404 that the pattern does not match the previous data P, it is determined whether or not the message string matches the flag pattern (S414). If it is determined that they match, P + 1 is added to the code string (S415), and P is further added (S41).
6). On the other hand, if it is determined in step 414 that the message string does not match the flag pattern, the previous value P is updated (S417), and the value is added to the code string, since the value may be used as it is as the code. (S416). Further, after executing the process of step 416, the process returns to step 402 to execute the above-described process.
This routine is continued until the end of the message data.

(5) Encoding example FIG. 5 is an explanatory diagram showing an example of encoding according to the present invention.
FIG. 5A shows data before encoding processing, that is, so-called transmission message data, and FIG. 5B shows data (code string) after encoding processing. Here, a case where the message strings M0 to M8 are encoded as shown in FIG. First, the first value is encoded as M0 → Q0 as it is. Next, since the value “3” of M1 is different from the value “1” of M0, this value is also encoded as it is. Since the subsequent value “3” of M2 is the same as the previous value “3” of M1, a flag indicating a continuous pattern is set in the code string.
In this case, (Q1 + 1), that is, "4" is set for Q2. In this case, since five values "3" are consecutive from M1 to M5, (Q1 + 5), that is, , "8" are set.

Subsequently, the data of M6 is referred to. In this case, since the last code values Q3 and M6 are different, Q4 has M
The value of 6 is set as it is. Further, since the value of M7 is different from Q4, it is set to Q5 as it is. At this time, M7 = (M6 + 1), which matches the flag pattern. Since Q6 indicates that the message itself is a flag pattern, the value "5" of Q4 + 0 is set. Finally, M8 is different from Q6, so the value is “4”
Set to Q7.

Accordingly, since the data thus encoded can be uniquely decoded into the original message data, the decoder 106 has only to process the above-mentioned encoding procedure in a reverse procedure. Will be.

(6) Decoding Procedure FIG. 6 is a flowchart showing a decoding procedure according to the present invention. First, one byte is extracted from the code string (S
601), a variable P for holding the previous code is initialized with the first code, and the P is added to the message sequence (S602). Next, 1-byte data read from the code string is set in a variable Q (S603), and it is determined whether or not all the code strings have been completed (S604). That is, the decoding process is executed until all the code strings are exhausted.

In step 604, when it is determined that the entire code sequence has been completed, the present routine is terminated. On the other hand, when it is determined that the code sequence has not been completed, it is determined whether or not the pattern is a flag pattern ( Detected) (S
605), if it is determined (detected) that the pattern is not a flag pattern, the code is added to the message as it is (S60).
6), the value of the variable P is updated (S607), and the process returns to step 603.

If it is determined (detected) in step 605 that the pattern is a flag pattern, one byte is extracted from the code string (S608), and the number C of continuous data is calculated (QP) (S609). Next, it is determined whether the number C of continuous data is 0 (S610).
At this time, when the number C is determined to be 0, it indicates that the original message itself was a flag pattern, and the same pattern (P +
1) is added (S611), and the process returns to step 603.

In step 610, the number C
Is not 0, it indicates that the data P is continuous C, so the data P is added to the message sequence C times (S612), and the variable P indicating the previous sign data is updated (S613). ), Returning to step 603.

(7) Decoding Example FIG. 7 is an explanatory diagram showing an example of decoding according to the present invention.
FIG. 7A shows a code sequence, and FIG. 7B shows a decoded sequence. Also, here, a case where decoding is performed on message data by a process reverse to the coding example described in FIG. 5 is shown, and code strings Q0 to Q7 are decoded. In the figure,
First, the first values Q1, Q2 are used as they are in the message M0,
Decode as M1. Since the subsequent Q2 has a flag start pattern of Q2 = (Q1 + 1), the number of continuous data is further obtained from Q3. That is, the number at this time is (Q3-
Q1) = (8-3) = 5. Therefore, five Q1 values “3” are set in the message sequence (M1 to M1).
5).

Next, reference is made to the code Q4. In this case Q
Since 3 and Q4 are different, the value "5" as it is is set in M6. Subsequently, referring to Q5, since this is also a flag pattern, the number is obtained by further referring to Q6. That is, the number in this case = Q6-Q4 = 0, and
It turns out that the flag pattern is the message itself. Therefore, the value “6” of Q5 is set as it is for M7. Finally, referring to Q7, Q7 is Q6
Does not become a flag pattern for
8 to end the decoding process in this case.

By the way, the encoder 101 in the present embodiment
It is conceivable that a code having a maximum length of twice the input data length is theoretically generated by the input data pattern. That is, this is a case where the input data pattern always matches the flag pattern. In consideration of such a case, a verification experiment was actually performed.

An MS operating on an 8086 microprocessor (manufactured by Intel Corporation, USA) based on this encoding method.
-Verification was performed on files generally handled in DOS. As a result, it was confirmed that a code string length can be reduced by about 10% in a normal executable file and about 50 to 90% in a bitmap image data as compared with input data. Therefore, unless data is intentionally created, the number of cases in which a long data string is generated for input data is extremely reduced. In a practical case, data compression is achieved simultaneously with encoding.

Therefore, as described in the present embodiment, the existing hardware configuration can be used as it is, and when compared with the conventional system, it is possible to obtain several times the data transmission efficiency and to reduce the data transmission efficiency. High-performance parallel data transmission is realized at low cost. In addition, according to this method, especially when bitmap image data is transmitted, the effect of the compression of the run length becomes remarkable, so that the transmission efficiency of image data requiring a large amount of data transmission is remarkably improved.

[0040]

As described above, according to the parallel data transmission device of the present invention, the encoding means uses the
Of one unit of data transmitted by the rel output means
Of the same data adjacent to each other
, Converted from the parallel output means through the transmission means and output in parallel from the parallel output means.
Of adjacent data with the same data
When converting to a code string composed of different data
When the transmission data sequence is a continuous data pattern, it is converted into a run length code to generate a code sequence, and the code sequence is output in parallel from the parallel output means via the transmission means. High-speed data transmission between a computer and a printer can be realized only by software control using hardware, and the economy and versatility of equipment can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a parallel data transmission device according to the present invention.

FIG. 2 is a flowchart showing an example of a data transmission procedure according to the present invention.

FIG. 3 is a flowchart showing an example of a data receiving procedure according to the present invention.

FIG. 4 is a flowchart showing an encoding procedure according to the present invention.

FIG. 5 is an explanatory diagram showing an example of encoding according to the present invention.

FIG. 6 is a flowchart showing a decoding procedure according to the present invention.

FIG. 7 is an explanatory diagram showing an example of decoding according to the present invention.

FIG. 8 is a timing chart showing general data transmission by a Centronics interface.

FIG. 9 is a flowchart showing a data transmission sequence shown in FIG. 8;

[Explanation of symbols]

Reference Signs List 101 encoder 102 transmission unit 103 parallel output port 104 parallel input port 105 reception unit 106 decoder

Claims (2)

(57) [Claims] A plurality of bit strings are defined as one unit of data,
Parallel output means for transmitting data in parallel for each data unit, and one unit transmitted by the parallel output means
Parts of the same data that are adjacent to each other
Method to convert to a code string composed of different data
A parallel data transmission apparatus comprising: a stage; and a transmitting unit that transmits a code sequence obtained by converting a transmission data sequence by the encoding unit to the parallel output unit. 2. A method according to claim 1, wherein a plurality of bit strings are defined as one unit of data.
Parallel output means for transmitting data in parallel for each data unit, and one unit transmitted by the parallel output means
Parts of the same data that are adjacent to each other
Into a code string composed of different data ,
Encoding means for converting the transmission data sequence into a continuous length code to form a code sequence when the transmission data sequence is a continuous data pattern, and converting the transmission data sequence by the encoding means into a parallel output means; And a transmitting means for transmitting the data to the parallel data transmission apparatus.