Abstract:
A programmable printer is provided which is capable of printing alphanumeric internally pre-stored data or data information and alphanumeric externally supplied data or data information either separately or in combination with each other. The alphanumeric printout of the printer may be inverted in a manner to allow its visual reading in what would otherwise be an &#34;upside-down&#34; configuration. The programmable printer incorporates a microprocessor for the proper addressing, interpretation and manipulation of input commands, timing information, paper-sensing information, external data information, and internal stored data information, so as to generate output information that seeks the desired data information, whether external or internal, and that drives a printer logic interface and output status lines and print drive interface so as to print the desired information and to monitor the status of the printer. The printer also includes an alphanumeric print mechanism incorporating twenty-one character columns per line of printout, a timing pulse generating means, a paper sensing means, and a lid detector switch; a printer logic interface that provides electrical isolation between the print mechanism and the microprocessor and provides the actuating power to operate the print mechanism&#39;s hammers as well as means for amplifying and shaping the timing pulses and paper sensing pulses from the print mechanism; a command interface that provides electrical isolation between the command information and the microprocessor as well as providing for the proper selection, shaping and timing of the command information; a data interface that provides electrical isolation between the external data information and the microprocessor as well as providing for the proper selection, shaping and timing of external or internal data information; a programmable &#34;read only&#34; memory for the storage of various messages; a set of output status lines for the transmission of information to the outside world and for the indication of various conditions of the printer; and a print drive interface that provides for the electrical isolation, shaping and amplification of the output status lines information and the print drive information.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a programmable printer, and more particularly to apparatus and methods employed therein. 
     The printer according to the invention disclosed herein is particularly adapted to an industrial environment so as to provide on line production monitoring and reporting. Such printers can be used to provide &#34;hard&#34; copy for plant supervisory and management personnel of essential data such as machine conditions, parts control, running time, tool life, and other desired industrial information. 
     In addition, the programmable printer herein disclosed is capable of printing both prestored data or data information and external data or data information, either individually or in combination with each other. The capability of intermixing stored data with external data allows the programmable printer to perform such functions as labeling external data so as to readily identify the external data, generating warning information when certain conditions exist in external machinery, generating diagnostic information regarding procedures to follow for correcting a machine malfunction, as well as many other industrial or non-industrial printing functions. Thus a statement such as &#34;LIMIT SWITCH No. 03 FAILED TO TRIP&#34; could be readily printed by the present invention upon receiving the required command and stored data addressing information as well as external data corresponding to the number &#34;03&#34;. 
     Present day printers are primarily made to print information only when such information is properly transferred to its machanisms. Unlike the present invention, most present day printers are not designed for harsh industrial environments. In addition, none of the present day printers are able to intermix prestored data with external data. Furthermore, none of the present day printers are compatible with present day programmable industrial controllers such as the Modicon Model 084 and Modicon Model 184, manufactured by the Modicon Corporation of Andover, Massachusetts. 
     The present invention allows such industrial controllers to initiate a printing sequence that causes the present invention to retrieve stored data which may in turn command the industrial controller to supply external data. The resulting printout consists of a message with both prestored and external data. 
     The only known prior art devices that are able to monitor external devices and initiate the production of stored data upon receiving particular command information are the prerecorded emergency message devices used on some aircraft. These devices warn the crew of such aircraft of particular emergency conditions, such as an engine fire. These devices however are not able to receive and display a variety of external data information, nor are they able to intermix external data information with prestored data information. 
     SUMMARY OF THE INVENTION 
     The programmable printer of the present invention performs the printing, in combination or individually, of stored data or data information and external data or data information. 
     The programmable printer includes a memory for the storing of alphanumeric data. This information may consist of up to 100 separately addressable messages, that may be printed by selecting a number related to its memory location. 
     A novel feature of the invention is the capability of the stored data messages to include blank spaces where the programmable printer tells an external device, such as an industrial programmable controller, that external data (generally variable data; e.g., a calendar date) is needed. Once the desired external data is received, the programmable printer returns to the stored data message for further printing. The stored data message may contain as many insertions of external data as desired, each time commanding an external data source to submit the desired external data. Thus a printed message may state, DATE 2/20/74, TIME 2:04 P.M., where &#34;DATE&#34;, &#34;/&#34;, &#34;/&#34;, &#34;TIME&#34;, &#34;:&#34; and &#34;P.M.&#34; are stored in the printer&#39;s memory and &#34;2&#34;, &#34;20&#34;, &#34;74&#34;, &#34;2&#34; and &#34;04&#34; are retrieved by commanding an external device to supply this data. 
     The printer incorporates a command multiplexer comprising input command lines, addressing lines and an output line. The printer also incorporates a microprocessor comprising a miniature fixed program digital computer. The microprocessor decodes and processes all incoming signals, as well as generating the proper output signals to perform the desired printing. 
     More particularly, the microprocessor continuously monitors all the incoming command lines of the command multiplexer. When the &#34;START FORM&#34; command line is in the true state (i.e., the &#34;START FORM&#34; signal is received), the multiplexer initiates a sequence of events. It first addresses the data multiplexers for the receipt of stored memory addressing information. The data interface consists of four 8-input, 1-output addressable multiplexer integrated circuits. Four of the input data lines of each multiplexer are for the receipt of external data, two of the lines are for the receipt of addressing information for the stored data, and two of the input lines are for the receipt of stored data. 
     The microprocessor thus retrieves eight lines of information related to a particular address location of the stored data. It receives this addressing information in a parallel fashion, four lines at a time. It interprets this address information as two binary coded decimal (BCD) numbers. Thus the eight addressing lines represent a decimal number from zero to 99, corresponding to the 100 addressable stored data locations of the printer&#39;s programmable &#34;read-only&#34; memory. 
     The programmable &#34;read-only&#34; memory (PROM) comprises nine 256 × 8, 2048 bit &#34;read-only&#34; memory chips. These chips contain all the prestored data messages that a particular user may require, up to 100 messages. 
     After the microprocessor receives the stored data addressing information from the data interface, it decodes and processes this addressing information in a manner to generate an output signal to drive a stored data selector. The stored data selector transforms this output information by means of output latches and demultiplexers to generate a chip selector signal which activates one of the PROM chips and which also activates a particular address location (PROM address) of the selected PROM. 
     The address memory location of the PROM selected generates eight bits of stored data output, which are connected to the data interface. The microprocessor then addresses the data interface to retrieve these eight bits of stored data information. The stored data information is interpreted in an ASCII code in order to allow printing of alphanumeric information. The microprocessor decodes and stores this information in an input memory buffer, while incrementing the stored data address location in order to receive the next eight bits of stored data. 
     If nothing further occurred, the microprocessor would store the next 21 ASCII characters from the selected PROM and would then generate output information to drive a printer logic interface and a print drive and output status lines interface. 
     The printer logic interface provides the necessary amplification and shaping of the microprocessor&#39;s hammer information in order to drive the print mechanism&#39;s hammers, which perform the actual printing. The print drive and output status lines interface amplifies and shapes the print drive information so as to control the paper drive of the print mechanism. The microprocessor also receives timing information from the print mechanism by the printer logic and command interfaces that causes the print mechanism&#39;s hammers to be activated at the proper time. 
     If the microprocessor receives particular stored data indicating that external data is desired, the microprocessor addresses the data interface so as to receive external data. At the same time the microprocessor indicates to the external device supplying the external data that external data is desired. This external data is similarly decoded and stored in the microprocessor buffer. 
     The microprocessor will continue to receive external data until the stored data indicates that no further external data is required, at which time the microprocessor will again decode and store the stored data. 
     Printing of the decoded data will occur every time 21 characters are stored in the microprocessor&#39;s input buffer or until a &#34;CARRIAGE-RETURN&#34; signal is received from the stored memory. The &#34;CARRIAGE-RETURN&#34; signal in essence generates a print command identical to the command initiated when 21 characters are stored in the microprocessor&#39;s buffer. 
     The programmable printer is also able to print external data without stored data. To perform this mode of printing the microprocessor must receive a &#34;LOAD BUFFER&#34; command from the command interface. This command causes the microprocessor to address the external data lines. The microprocessor then receives, decodes, and stores the external data on the external data line. The external data can be decoded in a BCD code or in an ASCII code, depending on the condition of the BCD/ASCII command line. If a BCD code is desired, one to four BCD digits may be received on the sixteen data input lines, depending upon the condition of two data-select lines of the command interface. If an ASCII code is desired, one or two ASCII digits may similarly be received on the same input lines. Once the data has been transferred to the microprocessor&#39;s input buffer, initiation of a print command will cause a print sequence to occur identical to that discussed above. A print command will also be generated if 21 characters are stored in the microprocessor&#39;s input buffer, as also discussed above. 
     The stored data is transfered from the PROMS to the microprocessor in parellel ASCII code. Thus by providing a common serial and parallel converter (not shown) the printer can accept serial ASCII coded external data. 
     The programmable printer also contains output status lines which monitor the various conditions of the printer; including, the condition of the print paper, whether a stored message is being printed, whether variable external data is desired in the stored message, and whether the print motor is operating. All of these output status lines, as well as all the input command lines and input external data lines, are electrically isolated from the programmable printer. In addition, the input data lines and the input command lines may be supplied to receive either 24-volt DC signals or 120-volt AC signals. Similarly the output status lines may be supplied to drive 24-volt DC devices or 120-volt AC devices. 
     OBJECTS OF THE INVENTION 
     It is therefore an object of the invention to provide a printer that is capable of printing, in combination, stored data and external data. 
     Another object of the invention is to provide a programmable printer capable of accepting external data in either a BCD or an ASCII code in parallel on ASCII code in serial. 
     A further object of the invention is to provide a programmable printer capable of printing in both an upright mode and in an inverted mode. 
     Another object of the invention is to provide a programmable printer with output status lines that monitor various conditions of the printer. 
     Another object of the invention is to provide output information capable of communicating with external devices with regard to receipt of external data. 
     An additional object of the present invention is to provide a programmable printer utilizing programmable &#34;read-only&#34; memories for the storage of internal prestored data messages. 
     A further object of the invention is to provide a programmable printer that electrically isolates all input and output communications with the outside world. 
     An additional object of the present invention is to provide a programmable printer that utilizes a specially programmed digital mini-computer for decoding and processing input commands and data information. 
     A further object of the present invention is to provide a programmable printer that provides &#34;hard&#34; copy to plant supervisory and management personnel of various machine conditions. 
     An additional object of the present invention is to provide a programmable printer capable of withstanding harsh industrial environments. 
     Other objects of the invention will in part be obvious and will in part appear hereinafter. 
    
    
     THE DRAWINGS 
     FIG. 1 is a block diagram of a programmable printer according to the invention; 
     FIG. 2 is a schematic diagram of the microprocessor shown in FIG. 1; 
     FIG. 3 is a schematic diagram of the command interface shown in FIG. 1; 
     FIG. 4, comprising FIGS. 4A and 4B is a schematic diagram of the data interface shown in FIG. 1; 
     FIG. 4C is a diagram showing how FIGS. 4A and 4B are put together to form FIG. 4; 
     FIG. 5 is a schematic diagram of the stored data selector shown in FIG. 1; 
     FIG. 6 is a schematic diagram of the programmable &#34;read only&#34; memory (PROM) shown in FIG. 1; 
     FIG. 7 is a schematic diagram of the print drive and output status lines interface shown in FIG. 1; 
     FIG. 8 comprising FIGS. 8A and 8B is a schematic diagram of the printer logic interface shown in FIG. 1; 
     FIG. 8C is a diagram showing how FIGS. 8A and 8B are put together to form FIG. 8; 
     FIG. 9 is a diagrammatic view of a print mechanism showing the generation of timing, fold detect, and lid detect information, as well as energization of print hammers, a print motor and a paper advance solenoid of the print mechanism; 
     FIG. 10 is a diagram of two output registers of an external device and how these output registers are connected to the programmable printer; 
     FIG. 11 is a diagram of an output register, a control apparatus, and three input lines of a Modicon 184 Programmable Controller; 
     FIG. 12 comprising FIGS. 12A, 12B, 12C, 12D, and 12E is an overall flow chart of a programmable printer according to the invention; 
     FIG. 12F is a diagram showing how FIGS. 12A, 12B, 12C, 12D, and 12E are put together to form FIG. 12; 
     FIG. 13 is a representation of the block diagrams used in FIGS. 12 and 14; 
     FIG. 14 comprising FIGS. 14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, and 14I is an overall flow chart of the computer program used by the microprocessor of the present invention; 
     FIG. 14J is a diagram showing how FIGS. 14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, and 14I are put together to form FIG. 14; 
     FIG. 15 is a truth table showing the number of characters generated when data select lines are in various states; 
     FIG. 16 is an illustration of all the line segments that may be generated by the print mechanism shown in FIG. 9; and 
     FIG. 17 is a diagrammatic view of the possible printout orientations of the print mechanism shown in FIG. 9. 
     FIG. 18 is a diagrammatic view of the printing drum of the print mechanism. 
    
    
     DETAILED DESCRIPTION 
     The System 
     As can best be seen in FIG. 1, a programmable printer 19 of the present invention can be considered to consist of a number of functional blocks. The functional blocks communicate with each other and with external devices in a novel manner to produce printing of stored data, external data or a combination of stored data and external data or data information. The stored data is located in the programmable &#34;read only&#34; memory (PROM) 21 while the external data is supplied by any external device, including a programmable controller 33, connected to the external data lines 27. 
     More particularly if only external data is to be printed, a microprocessor 20 receives from a command interface 22 all the incoming command signals 23 by sequentially addressing command interface address lines 24. When a &#34;LOAD BUFFER&#34; command is received by microprocessor 20 from the command interface 22, the microprocessor generates a data address 25 that retrieves from a data interface 26, external data 27 via data lines 28. The external data is then decoded and stored as individual characters in an input buffer 29 of microprocessor 20. The type and number of characters stored in the input buffer is dependent on incoming command signals, 23, retrieved by microprocessor 20, from the command interface 22. 
     If no further commands are received by the microprocessor the stored external data remains in the input buffer 29. However, upon receiving a print command 88 (see FIG. 3) from the command interface or upon the input buffer containing twenty-one characters of data, the microprocessor initiates a print sequence. The print sequence processes the decoded data and timing, paper sensing and lid detection information 30 received from the command interface 22 in order to generate hammer drive information 32, print drive information 34, and output status information 36. 
     The hammer drive information is fed into a printer logic interface 38, where it is shaped and amplified to generate a hammer drive 40. The hammer drive 40 is transferred to a print mechanism 42, to activate a set of print hammers 44 (see FIG. 9). The print drive information 34 is transferred to a print drive and output status lines interface 46 where it is amplified and shaped to generate a print drive 48. The print drive 48 is then transferred to a paper advance solenoid 50 (see FIG. 9) of the print mechanism 42 in order to advance the paper before the print hammers 44 are activated. Similarly, the output status information 36 is fed into the print drive and output status lines interface 46, where this information is shaped, amplified and electrically isolated so as to generate output status lines 54 capable of driving output status indicators 55 and external devices such as lights, relays, solenoids, and industrial programmable controllers via output lines 59. 
     When stored data or stored data and external data in combination are desired to be printed, the microprocessor 20 must receive a stored data printing initiation command from the command interface 22. This particular command, as shown in FIG. 3, is labeled &#34;START FORM&#34; 31. Upon receiving this command, the microprocessor 20 initiates a sequence of steps in order to retrieve, decode, and process the desired stored data along with any desired external data, 27. 
     More particularly, the microprocessor generates output status information 36 that is transferred to an external device via output lines 59. This output status information tells the external device that the programmable printer 19 is in a stored data sequence by enabling the &#34;FORM BUSY&#34; output line 57. 
     The microprocessor 20, also tells the external device that the programmable printer does not want external data by enabling the &#34;BUSY&#34; output line 61. 
     The microprocessor 20 also addresses the data interface 26 in order to receive the address of the desired stored data 60 via data lines 28. This addressing data is received by the data interface 26 from an external source such as an industrial programmable controller 33. 
     After the microprocessor 20 decodes the received addressing data it generates a stored data address information 62 that is transferred to the stored data selector 64. The stored data selector 64 generates a stored data address 66 that energizes the desired stored data location in the programmable &#34;read only&#34; memory (PROM) 21. 
     The PROM 21 transfers the data in the particularly addressed data location to stored data lines 70 that connect to the data interface 26. The microprocessor 20 retrieves this stored data by properly addressing the data interface 26 via the data address lines 25. The data is then decoded and stored in the microprocessor&#39;s input buffer 29. 
     The stored data is decoded in an ASCII code in order to retrieve alphanumeric information, and to provide for an alternative data interface 26 for receiving external data in ASCII serial code. As can be seen in Table 1, certain ASCII characters represent commands; e.g. &#34;END OF FORM&#34;, &#34;BELL&#34;, &#34;FORM FEED&#34;, &#34;CARRIAGE-RETURN&#34;, and &#34;ESCAPE&#34;. If an &#34;ESCAPE&#34; character is received, the microprocessor initiates the retrieval of external data by causing the &#34;BUSY&#34; output line 61 to become disabled. The disabled &#34;BUSY&#34; output line indicates to a connected external device; e.g., an industrial programmable printer 33, that external data has been requested by a stored data character. The external device then transfers external data to the data interface 26, and transfers commands 23 to the command interface 22, enabling the microprocessor 20 to properly interpret the external data. 
     Upon storing the decoded stored data if an &#34;ESCAPE&#34; character is not present, or upon storing the external data if an &#34;escape&#34; character is present, the microprocessor 20 increments the stored data address information 62 in order to retrieve the stored data in the next stored data location of PROM 21. This stored data will similarly be decoded by the microprocessor 20, generating another data character stored in the microprocessor&#39;s input buffer 29. 
     The above incrementation of the stored data address information 62 continues until either twenty-one characters are stored in the microprocessor&#39;s input buffer 29 or until a &#34;CARRIAGE-RETURN&#34; character is received from the stored data. In either event, the microprocessor 20 generates hammer drive information 32 and print drive information 34, which are transferred to the printer logic interface 38 and the print drive and output status lines interface 46, respectively. These respective interfaces generate hammer drive 40 and print drive 48 to properly energize the print hammer 44 and paper advance solenoid 50 of the print mechanism 42. Following the initiation of this print sequence, the incrementation of the stored data address information 62 resumes. 
     The above sequence of events will continue until an &#34;END OF FORM&#34; character is received from the PROM 21. This character causes the microprocessor 20 to terminate all the decoding and processing of stored data. The &#34;FORM BUSY&#34; 57 and &#34;BUSY&#34; 61 output lines will then be placed in a disabled state. 
     The printing of stored data, external data, or a combination of stored data and external data, will also be terminated by generation of a &#34;CLEAR&#34; signal 72. This signal and its inversion, generated by a clear interface 74, are transferred to the microprocessor 20. The microprocessor upon receipt of the clear and the inverted clear signal halts all decoding, retrieving and printing activity. The &#34;CLEAR&#34; signal 72 is the only command that the microprocessor 20 will accept when it is in a &#34;BUSY&#34; state; i.e., when the &#34;BUSY&#34; output line 61 is enabled. 
     The Method of Operation 
     As best seen in FIGS. 12A through 12E, the sequence of events that the programmable printer undertakes to print data may be represented as a series of processes, decisions and input and output operations (see FIG. 13). 
     More particularly, as best seen in FIGS. 1 and 12A, after initial power up, step 201, the programmable printer initiates an idle loop process, step 202. During the idle loop process, microprocessor 20 generates command interface address signals 24 that sequentially receive all the command timing, paper sensing and lid detection information 30 that the command interface 22 has received. During the idle loop, if the &#34;MOTOR STAY-ON&#34; command 80 (see FIG. 3) is in a true state, the printer starts and leaves on the printer motor 82 (see FIG. 9) no matter how long the time period before receipt of a dynamic command. 
     As best seen in FIG. 3, the dynamic commands consist of a &#34;PRINT&#34; command 88, &#34;SPACE&#34; command 90, &#34;LOAD BUFFER&#34; command 92, a &#34;FORM FEED&#34; command 94, and a &#34;START FORM&#34; command 31. A command is called a &#34;dynamic&#34; command when its detection by microprocessor 20 is achieved by sensing the command&#39;s change from a &#34;high&#34; electrical state to a &#34;low&#34; electrical state. 
     If a dynamic command has been received by microprocessor 20 in the last 30 seconds, the printer will leave the printer motor on, step 211. If the printer motor has not been energized prior to the receipt of a dynamic command, the receipt of such a command will start the printer motor, step 210. 
     The printer next determines if the retrieved dynamic command is a print initiation command, step 212. A print initiation command is a &#34;LOAD BUFFER&#34; command 92, a &#34;PRINT&#34; command 88 or a &#34;START FORM&#34; command 31. 
     If a print initiation command is present the printer determines whether the paper lid of the print mechanism 42 is open or closed, step 213. If the paper lid is open and thus indicating that paper is being attended to, the printer returns to the &#34;START&#34; position, step 202A. If the paper lid is closed, the printer allows the continuation of the print sequence and determines whether the printer is out of paper, step 214. If the printer is out of paper, the sequence returns to &#34;START&#34; since printing cannot be undertaken when the print mechanism 42 is out of paper. 
     If the print mechanism has paper and the paper lid is closed, the printer will proceed to clear all the print drive information 34 and hammer drive information 32 so that newly generated print drive and hammer information will not be misinterpreted by the print mechanism 42. 
     The printer then proceeds to generate print drive information 34 which will advance the paper to beyond the next fold in the paper, step 216. At this point the printer is ready to execute a sequence of steps that will print the desired data whether it be stored data or external data or a combination of stored data and external data. 
     If the print initiation command is for external data only, the printer proceeds to read the &#34;DATA SELECT&#34; lines 110, the &#34;ORIENTATION&#34; line 112, and the &#34;BCD/ASCII&#34; line 114 (see FIG. 3). The &#34;DATA SELECT&#34; lines 110 tell the microprocessor 20 how many characters of external data are to be received from the data interface 26. As can best be seen in FIG. 15, the &#34;DATA SELECT&#34; lines, depending on their states, will cause the microprocessor 20 to interpret the external data as either 1, 2, 3, or 4 BCD characters or 1 or 2 ASCII characters. 
     As seen in FIG. 12B, the printer proceeds to decode the retrieved external data in accordance with the state of the &#34;BCD/ASCII&#34; line, step 220. If the &#34;BCD/ASCII&#34; line 114 is in the true state; i.e., the 1 state, the external data is interpreted as binary coded decimal (BCD) information; i.e., numerical information. Similarly, if the &#34;BCD/ASCII&#34; line is in the false state; i.e., the zero state, the external data is interpreted as alphanumeric (ASCII) information. 
     Step 221 is present so as to determine if the external data is part of a stored data print sequence, in which case the printer returns to the stored data for further information. If however, as in the present case, the external data is to be printed without any internal stored data, the microprocessor 20 determines if twenty-one characters of information have been received by the microprocessor&#39;s input buffer 29, step 222. 
     If twenty-one characters have not been received, and if a &#34;PRINT&#34; command 88 has also not been received, the printer returns to &#34;RE-START&#34;, step 216A, where the printer re-initiates the sequence of steps of receive external data or stored data. 
     If twenty-one characters of data have not been received, but a &#34;PRINT&#34; command 88 has been received, the printer proceeds to initiate a sequence of steps to print the received data characters. Similarly, if twenty-one characters of data have been received, the printer will initiate a print sequence regardless of whether a &#34;PRINT&#34; command has been received. 
     When in the print sequence, the microprocessor 20 first retrieves timing information from the command interface 22, step 224. As is best seen in FIG. 9, this timing information comprises a &#34;RESET HEAD&#34; signal 124 and a &#34;TIMING HEAD&#34; signal 126. The &#34;RESET HEAD&#34; signal causes the print operation to be synchronized with the revolutions of the print drum 128 so that the print hammers 44 will only be activated after the print drum 128 has returned to a starting position. The &#34;TIMING HEAD&#34; signal is used by the microprocessor 20 to cause the print hammers 44 to be activated at the proper time to cause the hammers to engage with the print drum line segments 130. 
     The microprocessor 20 next determines the desired orientation that the print-out 132 (see FIG. 16) is to have. This information is received on the &#34;ORIENTATION&#34; command of the command interface 22. The microprocessor 20 is able to generate hammer drive information 32, in accordance with the true or false state of the &#34;ORIENTATION&#34; command, so as to produce either upright or inverted printout (see FIG. 16). 
     Once the microprocessor 20 determines the orientation of the print-out 132, it processes the decoded data to generate hammer drive information 34. This hammer drive information is timed so as to be in synchronization with the print drum 128 and the print drum line segments 130. 
     More particularly the hammer drive information 32 must cause the print hammers 44 to strike the print drum line segments 130 in such a manner that the desired character is generated. As best seen in FIGS. 9 and 18 the print mechanism comprises twenty-one hammers that generate up to twenty-one characters per line of printout. The print mechanism 42 utilizes a Seiko Model AN-101S printer. This printer is capable of generating alphanumeric characters by striking print drum line segments 130 in a particular manner for each character. As best seen in FIG. 17 the line segments form a &#34;star-burst&#34; pattern. As best seen in FIG. 18, each of the line segments shown in FIG. 17 are evenly spaced about the circumference of the print drum 128 for each of the twenty-one character positions. Thus in order to generate a &#34;7&#34;, line segments 136, 140 and 142 would be struck as they appeared under a particular print hammer. Similarly a leter &#34;B&#34; would be generated by striking line segments 136, 140, 142, 146, 148, 150, 152, and 154 when those line segments appeared under the print hammer 44. Thus up to twenty-one alphanumeric characters may be printed per line of print-out 132. 
     The hammer drive information 32 must therefor energize the print hammers 44 at the proper time for each desired character to be generated during each line of printout. 
     The microprocessor also generates print drive information 34 to cause the advance of the print paper each time a line of printout is generated. The print drive information 44 causes the print drive 48 to be generated by the print drive and output status interface 46. 
     The microprocessor 20 also generates output status informaion 36 which causes output lines 59 to be energized via the print drive and output status lines interface 46. This information is electrically isolated from the programmable printer 19 and may be used to drive relays, solenoids or other external devices such as industrial programmable controllers 33, including the Modicon Model 084 and 184 Programmable Controllers. As best seen in FIG. 12C if the programmable printer 19 is not executing a stored data print initiation command, it returns to &#34;START&#34;, step 202A, after printing external data. The printer then proceeds to retrieve, decode, and process additional data upon the proper commands being received by the microprocessor 20 via the command interface 22. 
     If the printing of stored data; i.e., data stored in the programmable &#34;read only&#34; memory (PROM) 21 is desired the programmable printer 19 follows the same sequence of steps as for the external data printing as shown in FIGS. 12A and 12B up to and including step 227. 
     As shown in FIG. 3 the command that initiates the print sequence to generate printout of stored data is the &#34;START FORM&#34; command 31. As shown in FIGS. 1 and 12B, upon receipt of such a command the programmable printer 19 enables output lines &#34;FORM BUSY&#34; 57 and &#34;BUSY&#34; 61 that tell external data source devices, such as an industrial programmable controller 33, that stored data is to be printed, step 229. 
     The microprocessor 20 then proceeds to retrieve the address of the desired stored data. The microprocessor obtains this desired address by generating a data address 25 which retrieves from the data interface 26 the address of the desired stored data. This address is interpreted by the microprocessor 20 to be a decimal number from zero to 99 corresponding to one of the 100 possible externally addressable stored data locations in the programmable &#34;read only&#34; memory 21. 
     As best seen in FIGS. 1 and 6, the microprocessor then produces a stored data address information 62 which provides the information needed by the stored data selector 64 to generate a stored data address 66. The stored data address consists of a chip selector output 157 that locates the memory chip 98 of the PROM 68 in which the stored data is located, as well as a chip address 158 that locates the desired stored data in the energized chip. 
     This desired stored data is then produced on the stored data lines 70 (See FIGS. 1 and 6) and fed into the data interface 26. The microprocessor 20 retrieves this stored data from the data interface by generating the proper data address 25 to the data interface 26. 
     The microprocessor 20 proceeds to decode the stored data in order to obtain the particular ASCII character that the eight lines of stored data 70 represent. All stored data in the programmable &#34;read only&#34; memory 21 is in the ASCII code so as to enable the generation of alphanumeric characters. As seen in Table 1, an ASCII character may be a command character which causes the microprocessor to initiate or terminate a sequence of steps. 
     
                       TABLE 1______________________________________ASCII CODE 8-Bit            8-Bit            8-BitChar- Code (in Char-   Code (in                         Char-     Code (inacter octal)   acter   octal) acter     octal)______________________________________A     301      1       261    =         275B     302      2       262    &gt;         276C     303      3       263    ?         277D     304      4       264              300E     305      5       265    [         333F     306      6       266              334G     307      7       267    ]         335H     310      8       270    ↑   336I     311      9       271    ←    337J     312K     313      !       241L     314      &#34;       242M     315              243N     316      $       244    END OF FORM                                   204O     317      %       245    BELL      207P     320      &amp;       246    FORM FEED 214Q     321      &#39;       247    CARRIAGE  215R     322      (       250    RETURNS     323      )       251    ESCAPE    233T     324      *       252    SPACE     240U     325      +       253V     326      ,       254W     327      -       255X     330      .       256Y     331      /       257Z     332      :       272          ;       2730     260      &lt;       274______________________________________ 
    
     More particularly if the stored data retrieved and decoded by the microprocessor is an &#34;ESCAPE&#34; character, denoted by octal code 233 (see Table 1), the programmable printer 19 proceeds to retrieve external data, step 237 (see FIG. 12D). If an &#34;ESCAPE&#34; character is not present, the printer continues to interpret the stored data character. 
     As best seen in FIGS. 1 and 12D, if an &#34;ESCAPE&#34; character is present, the microprocessor 20 disables its &#34;BUSY&#34; output line 61, and thus tells a connected external device such as an industrial programmable controller 33 that external data is required. 
     As seen in FIG. 11 with respect to a Modicon Model 184 Programmable Controller, the disabling of the printer&#39;s &#34;BUSY&#34; output line 61 de-activates Coil No. 396 that is connected to this output line. The de-activation of Coil No. 396 causes BUSY RELAY NO. 1092 to open thereby allowing the programmable controller to supply external data via use of the Data Transfer Function 100 as described in &#34;Modicon Model 184&#34; 1973 brochure; Modicon Corporation, Andover, Massachusetts. Upon receipt of such a signal the Modicon Model 184 Programmable Controller generates BCD data (see Table 2) on Bit numbers 4, 5, 6 and 7 of output register No. XXX. This BCD data is transferred to the data interface 26 where the microprocessor 20 is able to retrieve the data by properly addressing the data interface. 
     
                       TABLE 2______________________________________BCD CODEDecimal            8     4     2   1Digits             b.sub.3                    b.sub.2                          b.sub.1                              b.sub.0______________________________________0                  0     0     0   01                  0     0     0   12                  0     0     1   03                  0     0     1   14                  0     1     0   05                  0     1     0   16                  0     1     1   07                  0     1     1   18                  1     0     0   09                  1     0     0   1______________________________________ 
    
     Similarly, as seen in FIG. 10, an external device can generate external data on its Register No. 0, Bit Nos. 0-3, 6-9, 12-15, and 18-21, when the &#34;BUSY&#34; line is disabled on Register No. 1, Bit No. 6. Between the time that the microprocessor disables the &#34;BUSY&#34; output line 61 and the generation by an external device of the appropriate external data 27 (see FIG. 1), the microprocessor waits for the external device to generate an external data printing initiation command, step 238. For the retrieval of external data a &#34;LOAD BUFFER&#34; command 92 is generated (see FIGS. 10 and 11). 
     The sequence of events in retrieving the external data, including the receipt of the &#34;LOAD BUFFER&#34; command proceeds in an analogous fashion to the retrieval of &#34;external data only&#34;. More particularly the sequence of events returns to and proceeds from the &#34;EX-START&#34; position, step 217A of the flow chart (FIG. 12B). 
     If the decoded stored data at Step 235 is not an &#34;ESCAPE&#34; character, the microprocessor 20 determines whether a &#34;LINE FEED&#34; is desired, Step 236. A &#34;LINE FEED&#34; causes the paper advance solenoid 50 (see FIG. 9) to energize causing the paper to unroll an amount equal to one line of printout. As shown in Steps 240 and 240A the &#34;LINE FEED&#34; command generates twenty-one &#34;SPACE&#34; characters that are placed in input buffer 29 of microprocessor 20. A &#34;SPACE&#34; command is a character that when processed by the microprocessor generates no hammer activation. Thus when twenty-one such characters are in the input buffer 29 a print sequence, Step 222A, is initiated where no printout occurs. As shown in FIG. 14C upon completion of the print sequence the microprocessor returns to &#34;S START&#34;, Step 230A, to continue the retrieval of additional stored data. 
     As seen in FIG. 12D, if the retrieved stored data is not an &#34;ESCAPE&#34; character nor a &#34;LINE FEED&#34; character the microprocessor determines whether twenty-one characters of data have been received, Step 239. If twenty-one characters of data are in the microprocessor&#39;s input buffer 29 or if a &#34;CARRIAGE RETURN&#34; character is present in the last decoded stored data character, a print sequence is initiated, Step 222A. This print sequence is identical to the print sequence for the &#34;external data only&#34; situation. 
     If neither twenty-one characters of data have been received by input buffer 29 nor a &#34;CARRIAGE RETURN&#34; character has been decoded from the stored data, the flow chart proceeds to Step 242 where it is determined whether the decoded stored data character is an &#34;END OF FORM&#34; character. If the last stored data character in input buffer 29 is not an &#34;END OF FORM&#34; character the printer will continue to retrieve, decode and process more data by incrementing the stored data address, Step 243, and returning to &#34;S START&#34;, Step 230A. If the last character of stored data in the input buffer 29 is an &#34;END OF FORM&#34; character, the microprocessor will conclude that the stored data information retrieval should be terminated and that external devices, such as industrial programmable controllers 33 (see FIG. 1) should be told that the programmable printer is no longer in the process of printing stored data with or without external data. After an &#34;END OF FORM&#34; character is retrieved, the printer disables the &#34;FORM BUSY&#34; 61 and &#34;BUSY&#34; 57 output lines and returns to the &#34;START&#34; position, Step 202A, where it is ready to receive a command to initiate &#34;external data only&#34; printing or &#34;stored data with or without external data&#34; printing. 
     Thus as shown in FIGS. 12A through FIG. 12E, once the programmable printer 19 is powered up, Step 201, it functionally proceeds through a sequence of events where it receives command information to perform the retrieval, decoding, processing, and transferring of data - whether it be stored data within the programmable printer or external data - to a print mechanism that is capable of responding to the generated output information so as to yield a desired print-out 132. 
     Examples 
     An example of the programmable printer&#39;s ability to print stored data is the following: 
     Limit switch no. 3 
     failed to switch 
     check the following: 
     1. tool alignment 
     2. casting mount 
     3. limit switch 
     malfunction. 
     in order to print the above message, it would be necessary to have each line of desired printout to be stored in sequential memory locations of the programmable &#34;read only&#34; memory 21 (see FIG. 1). It would also be necessary to set the stored data address lines 60 to a binary coded decimal number that is related to this particular message. If, for instance, the first line of the above message corresponded to the 10th externally addressable stored data location of the programmable &#34;read only&#34; memory, it would be necessary to set stored data address lines 0, 1, 2, 3 to a BCD &#34;0&#34; while setting stored data address lines 4, 5, 6, and 7 to a BCD &#34;1&#34;. 
     Following this operation, a &#34;START FORM&#34; command would be necessary on command interface 22. If the last line of the above message contained an &#34;END OF FORM&#34; ASCII character, the printing of the above message would terminate after the printing of &#34;MALFUNCTION&#34;. The &#34;END OF FORM&#34; character as well as the &#34;CARRIAGE-RETURN&#34; ASCII characters following each line of printout (to initiate the printing of each line), would be stored in the programmable &#34;read only&#34; memory 21. 
     If only the external data number &#34;4372&#34; is desired to be printed, the following operations are necessary (see FIG. 3): 
     1. enable the BCD/ASCII line 114 on command interface 22; 
     2. Set BCD digits corresponding to decimal numbers 4, 3, 7, 2 on the sixteen external data lines 27, in the following order: 
     a. a BCD &#34;4&#34; on external data lines 0, 1, 2 and 3; 
     b. a BCD digit &#34;3&#34; on external data lines 4, 5, 6, and 7; 
     c. a BCD digit &#34;7&#34; on external data lines 8, 9, 10 and 11; 
     d. a BCD digit &#34;2&#34; on external data lines 12, 13, 14, and 15; 
     3. Enable &#34;DATA SELECT 0&#34; and &#34;DATA SELECT 1&#34; 
     lines 110; 
     4. Give a &#34;LOAD BUFFER&#34; command 92; and 
     5. Give a &#34;PRINT&#34; command 88. 
     Similarly, if an external data letter &#34;X&#34; is desired to be printed, the following operations are necessary: 
     1. Disable the BCD/ASCII line 114; 
     2. Set an ASCII letter &#34;X&#34; on external data lines 27, numbers 8, 9, 10, 11, 12, 13, 14, and 15; 
     3. Disable both &#34;DATA SELECT 0&#34; and &#34;DATA SELECT 1&#34; lines 110; 
     4. Give a &#34;LOAD BUFFER&#34; command 92; and 
     5. Give a &#34;PRINT&#34; command 88. 
     Finally, an example of a stored data message requiring external data will be given. A typical message might be: 
     Output of machine s 
     data ss-ss-ss 
     shipped s 
     parts count s s s; 
     where &#34;S&#34; denotes the retrieval of external data. 
     To print this message it is again necessary to set the stored data address lines of the data interface 26 to correspond to the externally addressable stored data location of the first line of printout. Second, a &#34;START FORM&#34;  command 31 is given. At this point the &#34;FORM BUSY&#34; and &#34;BUSY&#34; output signals are enabled. At the &#34;S&#34; characters in each line of printout the &#34;BUSY&#34; output line 61 becomes disabled allowing variable data to be inserted on external data lines 27. This insertion of external data is similar to the displaying of external data as given in the second example. 
     Thus, 
     1. Enable BCD/ASCII line 114 so that a BCD character can be decoded; 
     2. Set four bits of data on external data lines numbers 12, 13, 14, and 15 corresponding to the desired decimal number of the machine; 
     3. Disable &#34;DATA SELECT 0&#34; and &#34;DATA SELECT 1&#34; lines 110; and 
     4. Give a &#34;LOAD BUFFER&#34; command 92. 
     At each additional point in the message where an &#34;S&#34; character appears the &#34;BUSY&#34; output signal 61 is disabled and external data is inserted. At each such point the &#34;BCD/ASCII&#34;, &#34;DATA SELECT 0&#34; and &#34;DATA SELECT 1&#34;, and the external data lines have to be set to give the proper data in the form desired before the &#34;LOAD BUFFER&#34; command is given. 
     The Functional Blocks 
     The functional blocks of the present invention primarily consist of integrated circuit chips that perform various logic functions. In addition some of the functional blocks include other solid state components such as diodes, transistors, as well as conventional circuit components, such as resistors, capacitors and transformers. 
     As best seen in FIG. 2, microprocessor 20 consists of a group of integrated circuit chips which, in combination, perform as a digital computer. 
     More particularly, microprocessor 20 incorporates five programmable &#34;read only&#34; memories 156 wherein a specially formed computer program is stored that enables the microprocessor to decode and process all incoming command and data information as well as providing for the generation of output information including the hammer drive information 32, print drive information 34, output status information 36, stored data address information 62, data address information 25, and command interface address 24. The PROM&#39;s are ultraviolet &#34;read only&#34; memories manufactured by Intel Corporation, Part No. 1702A. As shown in FIG. 2, each PROM contains eight address lines and eight output lines, wherein eight bits of program information may be obtained by properly addressing the PROM. A chip select line 159 is included to activate the PROM containing the desired program information. 
     Microprocessor 20 also incorporates an address interface 160 (Intel Corporation, Part No. 4008) for addressing the PROM chips. The address information to address interface 160 comes from the output of the central processing unit (Intel Corporation, Part. No. 4004) 162. The central processing unit (CPU) is designed to be used with address interface 160, programmable &#34;read only&#34; memories (PROM) 156, central processing unit interface 164, random access memories (RAM) 166, chip selector latch 168, input buffers 29, and output latch 170 so as to provide a digital mini-computer. 
     The CPU 162 consists of a 4 bit adder, a 64 bit (16 × 4) index register, a 48 bit (4 × 12) program counter and stack, an address incrementer, an 8 bit instruction register and decoder, and control logic. Information flows from the CPU and the other microprocessor chips through a four line data bus 172. In a typical machine cycle the CPU 162 sends a synchronization signal (SYNC) 174 to the PROM&#39;s 156 and the RAM&#39;s 166. The CPU 162 then transmits 12 bits of PROM address information on data bus 7 by using three clock cycles. The PROM address information is then incremented by one and stored in the program counter. The selected PROM 162 sends back eight bits of instruction data during the following two clock cycles. This information is stored in an OPR register and an OPA register. The next three clock cycles are then used to execute the instruction transferred by the PROM 156. The instruction set of the CPU 162 is contained in Tables 3A, 3B, and 3C. 
     The PROM&#39;s 156 are controlled by a command PROM control signal (CM-PROM) 180 while the RAM&#39;s are controlled by RAM control signals (CM-RAM) 182. 
     The RAM&#39;s 166 (Intel Corporation, Part. No. 4002) allow the microprocessor to communicate with peripheral devices. As can be seen in FIGS. 1, 2, 3, 4, 5, 7 and 8, command interface address 24, hammer drive information 32, print drive information 34, output status information 36 and stored data address information 62 are totally or partially generated by RAM&#39;s 166. Other RAM&#39;s are used by microprocessor 20 for the storage of various computational information. 
     The central processing unit interface 164 provides the proper interfacing between the PROM&#39;s 156 and the central processing unit 162. 
     The chip selector 168 provides for the activation of the selected PROM 156 upon retrieving this information from the address interface 160. ##SPC1## 
     The input buffers 29 provide for the proper electrical isolation of incoming data information 28 (see FIG. 1). 
     The output latch 170 provides the electrical isolation of microprocessor 20 from stored data selector 64 and data interface 26. 
     The computer program that microprocessor 20 utilizes in order to retrieve, decode and process stored data, external data, command timing, paper sensing and lid detection information, so as to produce the required output information to cause the programmable printer to print the desired data and other output information is reproduced in Table No. 4. As can best be seen in FIG. 14A through J, the flow chart of the computer program comprises a multiplicity of operations including initial power up (FIG. 14A), command detection (FIG. 14B), retrieval of exteral data (FIG. 14C), paper condition monitoring and paper feeding (FIG. 14D), timing synchronization of the output information (FIG. 14E), line feeding (FIG. 14F), paper and lid sensing (FIG. 14G), retrieving timing information from the print mechanism 42 (FIG. 14H), and detection of command information (FIG. 14I). It is thus apparent that the microprocessor 20 performs substantially all the information manipulation of the programmable printer, as discussed earlier in the &#34;Method of Operation&#34;. ##SPC2## ##SPC3## ##SPC4## ##SPC5## ##SPC6## 
     As can best be seen in FIG. 3, command interface 22 basically comprises a 16 input addressable command multiplexer 184 (Texas Instrument, Part No. SN 74150). The inputs to the command mutiplexer 184 are the print reset pulse 124, the print timing pulse 126, a PRINT command 88, a SPACE command 90, a LOAD BUFFER command 92, a FORM FEED command 94, a START FORM command 31, a MOTOR STAY ON command 80, a DATA SELECT 0 and DATA SELECT 1 command 110, an ORIENTATION command 112, a BCD/ASCII command 114, a LID DETECT signal 186, a FOLD DETECT signal 188, and a MANUAL ADVANCE command 190. The MANUAL ADVANCE command 190 incorporates inverter 192 and nor gate 194 for the proper conditioning of this command. The resistor 196 is used for current limiting LID DETECT signal 186. The output of multiplexer 184 is inverted by the inverter 198 and transferred to microprocessor 20. Command addressing information is obtained from the microprocessor via outputs RAM 0-0 to RAM 0-3. These four addressing lines sequentially sample all the input command information received by multiplexer 184, thereby obtaining an output signal that time samples all the input command information. All of the incoming commands from external devices 33 are first electrically isolated, shaped and amplified by D.C. input modules or A.C. input modules as discussed below with respect to data interface 26. 
     As best seen in FIGS. 4A and 4B the data interface 26 comprises input modules 300 and 302 for electrically isolating external data information and stored data address information (see FIG. 4A). As best seen in FIG. 4B, data interface 26 also comprises four multiplexers 304 for selectively channeling said external data, stored data address information, and stored data. Multiplexers 304 (Texas Instruments, Part No. SN74151A) are addressed by the outputs of microprocessor latch 170; i.e., ROM 00-1 to ROM 00-3. The output of data interface 26 consists of four output lines, ROMI-1-0 to ROMI-1-3, which are received by microprocessor 20 in input buffers 29. 
     When external data or stored data address information are of a direct voltage nature, input module 300 is used to provide the correct input information to multiplexers 304. The list of the components used in input module 300 are contained in Table No. 5. Basically the input module utilizes an optical coupler 4-5 to isolate the input information from an external device. This information is then amplified by operational amplifier 4-12 and transistor 4-15. 
     Input module 302 is utilized if the external data information or stored data address information is in an alternating voltage mode. A list of the components used will be found in Table 6. Basically this input mode utilizes an input energy threshold means via capacitors 4-21 and 4-24 and thyristor 4-26, to allow the generation of an output signal to the data interface multiplexer 304 when the energy level of the input alternating voltage signal is greater than a predetermined level. 
     Alternatively the printer 19 may take the form of a general purpose computer compatible printer. Such printers are usually supplied with ASCII coded characters on serial data lines. The data may be supplied at a rate of 110 or 300 band (corresponding to 10 or 30 characters per second) in accordance with the Electrical Industry Standard RS232C or on so called 60 or 20 milliamps current loop channels. 
     A printer which is designed to receive such serial ASCII data employs a data interface 26 comprising a serial to parallel data converter known in the art as U/ART (universal asynchronous receiver transmitter). For example, a Texas Instrument&#39;s model TMS6011. 
     The output of the U/ART is supplied on data lines 28 (FIG. 1) to the input buffer 29 of the microprocessor 20. 
     If it is desired to print stored serial coded ASCII data, the information on the stored data lines 70 is appropriately multiplexed with the outputs from the U/ART in a manner similar to that illustrated in FIG. 4B. 
     
                       TABLE 5______________________________________DATA INTERFACE -- D. C. INPUT MODULENumber         Component______________________________________4-1            10K4-2            Diode IN40074-3            931 ohm4-4            Diode IN41484-5            LED-Phototransistor4-6            470 pf4-7            2.2K4-8            33.2K4-9            0.33 μfd4-10           33.2K4-11           221K4-12           Operational Amplifier4-13           2.2 meg4-14           5.1K4-15           Transistor (RCA No. CA3086)4-16           5.1K4-17           51 ohm4-18           10 ohm4-19           1.0 μfd______________________________________ 
    
     
                       TABLE 6______________________________________DATA INTERFACE -- A. C. INPUT MODULENumber           Component______________________________________4-20             510 ohm4-21             0.56 μfd4-22             27K4-23             27K4-24             0.1 μfd4-25             6.2K4-26             Thyristor4-27             Transformer4-28             100 ohm4-29             51 ohm4-30             51 ohm4-31             .01 μfd4-32             Diode IN41484-33             Diode IN41484-34             470 ohm4-35             Transistor 2N44014-36             10 ohm4-37             100 ohm4-38             Diode IN9144-39             .01 μfd4-40             Inverter______________________________________ 
    
     As can best be seen in FIG. 6, programmable &#34;read only&#34; memory (PROM) 21 consists of nine ultraviolet memory chips (Intel Corporation, Part No. 702A) 98. These memory chips are identical to the programmable &#34;read only&#34; memories 156 of microprocessor 20. The PROM&#39;s 98 are activated by chip selector outputs 157 from stored data selector 64. Likewise the particular memory address location of the selected PROM 98 is obtained via the eight chip address lines 58, from stored data selector 64. The output of the selected PROM data location is transferred to eight stored data lines 70 and transferred thereby to data interface 26. 
     As best seen in FIGS. 8A and 8B, printer logic interface 38 comprises timing information and fold detection information amplification and shaping (FIG. 8A) as well as providing amplification and shaping to hammer drive information 32, so as to generate hammer drive 40. A table of the electronic components utilized in amplifying and shaping the timing information 124 and 126 as well as fold detect signal 127 is contained in Table 7. Since the reset head signals 124 and the timing head signals 126 are generated by magnetic means (see FIG. 9) the circuitry shown in FIG. 8A basically shapes this pulse information so as to be compatible with command multiplexer 184. 
     
                       TABLE 7______________________________________PRINTER LOGIC INTERFACENumber         Component______________________________________8-1            1K8-2            2.37K8-3            4.22K8-4            511 ohm8-5            19.6K8-6            1K8-7            1.33K8-8            4.22K8-9            511 ohm8-10           19.6K8-11           1.33K8-12           19.6K8-13           19.6K8-14           100 ohm8-15           100 ohm8-16           30K8-17           10 μfd8-18           0.01 μfd8-19           0.01 μfd8-20           0.01 μfd8-21           0.01 μfd8-22           0.05 μfd8-23           Nor Gate8-24           And Gate8-25           Inverted or Gate8-26           Flip-Flop8-27           Nor Gate8-28           Operational Amplifier8-29           Operational Amplifier8-30           And Gate8-31           And Gate8-32           1K8-34           Zener Diode IN7468-35           Diode IN9148-36           Zener Diode IN7468-37           Diode IN914______________________________________ 
    
     Likewise since the fold detect signal 127 is generated by an optical device (see FIG. 9), it is shaped and amplified by the printer logic interface to be compatible with command multiplexer 184. 
     As shown in FIG. 8B, the printer logic interface 38 retrieves a serial hammer drive information 32 and generates a parallel output hammer drive 40. The printer logic interface 38 utilizes three shift registers (Intel Corporation, Part No. 4003) to receive the serial hammer drive information 32 and generate twenty-one parallel output signals 306. These output signals are then amplified via inverters 308 and relay drivers 310. The outputs of the relay drivers 310 generate the hammer drive 40 which is transferred to print mechanism 42 to drive the print hammers 46. 
     As can best be seen in FIGS. 9 and 18, print mechanism 42 comprises a print drum 128 incorporating arrays of line segments 130. Reset head signal 124 is generated by magnetic slug 312 passing in proximity to pick-up coil 314. Timing head disc 316 is mechanically coupled to print drum 128 in a gear ratio of 16 to 1. Therefore timing head disc 316 makes 16 revolutions per one revolution of print drum 128. Magnetic slugs 318 in combination with pick-up coil 320 generate two timing head pulses per revolution of timing head disc 316. These timing pulses provide the proper synchronization of hammer drive 40 so that the desired line segments 130 are properly struck by print hammers 44. 
     Fold detect signal 127 is generated by detecting holes in the print paper via light emitting diode - photo transistor combination 322 and operational amplifier 324. 
     As seen in FIG. 9, hammer drive 40 activates hammer solenoid 326, causing print hammers 44 to engage with print paper 328. 
     Print motor 329 is activated by motor signal 330 while paper advance solenoid 50 is activated by paper advance solenoid signal 322. Lid detect signal 186 is generated by switch 336 connected to the paper lid enclosing paper 328. 
     As best seen in FIG. 7, print drive and output status lines interface 46 incorporates a motor drive and paper feed module 328, a direct current output module 330, and an alternating current output module 332. The components used in the print drive and output status interface 46 are listed in Table 8. 
     More particularly motor drive and paper feed module 328 incorporates &#34;Positive - And&#34; driver 7-19 (Texas Instruments, Part No. 75450) which, when amplified by transistors 7-24 and 7-27 with peripheral circuitry, provides the motor signals 330 and paper advance solenoid signal 331. 
     
                       TABLE 8______________________________________PRINT DRIVE AND OUTPUT STATUSINTERFACE COMPONENTSNumber         Component7-1            IN41487-2            LED-phototransistor7-3            360 ohm7-4            47OPF7-5            33.2K7-6            10K7-7            0.33 μfd7-8            33.2K7-9            221K7-10           2.2MEG7-11           Operational Amplifier7-12           2N49237-13           360 ohm7-14           1K7-15           2N49237-16           1N40077-17           1N40077-18           20K7-19           75450 Texas Instruments7-20           Output Latches, SN74174          Texas Instruments7-21           Output Latches, SN74174          Texas Instruments7-22           Output Latches, SN74174          Texas Instruments7-23           2207-24           Transistor7-25           0.01 μfd7-26           220 ohm7-27           Transistor7-28           10 ohm7-29           0.01 μfd7-30           IN40077-31           0.01 μfd7-32           1K7-33           0.002 μfd7-34           1K7-35           2N44037-36           470 ohm7-37           IN9147-38           4.7K7-39           4.7K7-40           27K7-41           0.1 μfd7-42           2N60277-43           Transformer7-44           47 ohm7-45           0.002 μfd7-46           Thyristor7-47           47 ohm7-48           0.05 μfd7-49           Bi-polar diode______________________________________ 
    
     The direct current output module 330 electrically isolates the output of latch 7-21 (Texas Instruments, Part No. SN74174) via light emitting diode - phototransistor combination 7-2. This signal is amplified by operational amplifier 7-11, transistor 7-12, and transistor 7-15, in combination with the remainder of the circuitry of DC output module 330. 
     Alternating current output module 332 incorporates transformer 7-43 for electrically isolating the 120 volt AC output signal from the output latches. The output module 332 incorporates transistor 7-35 and 
     7-42 for properly shaping pulse information applied to transformer 7-43. The secondary side of transformer 7-43 is coupled to thyristor 7-46 so as to activate the thyristor when transformer 7-43 receives a pulse. Activation of thyristor 7-46 allows generation of 120 volt AC output signals. 
     It should be noted that the &#34;BUSY&#34;, &#34;FORM BUSY&#34;, &#34;PAPER OUT&#34;, and &#34;BELL&#34; signals may be applied to either a 24 volt DC output module 330 or a 120 volt AC output module 332. 
     The clocking information 334 transferred to output latches 7-20, 7-21, and 7-22 is generated by stored data selector 64. The information relating to the MOTOR DRIVER, PAPER FEED, MOTOR ON, BUSY, FORM BUSY, PAPER OUT, and BELL signals is generated by microprocessor 20 and transferred to print drive output status lines interface 46 via print drive information 34 and output status information 36. 
     As can best be seen in FIG. 5, stored data selector 64 comprises a group of integrated circuits. The demultiplexer 336 (Texas Instruments, Part No. SN74155) demultiplexes stored data address information 62 generated by microprocessor 20. The outputs of demultiplexer 336 provide the clocking information used in print drive and output status lines interface 46 as well as the clocking information used in output latches (Texas Instruments, Part No. 74174) 338, 340, and 342. The outputs of output latches 338 and 340 combine to form the chip address 158 of the selected programmable &#34;read only&#34; memory chip 98. The output of output latch 342 is applied to demultiplexer 344 (Texas Instruments, Part No. 74155). One of the outputs of demultiplexer 344 is activated, corresponding to the desired programmable &#34;read only&#34; memory chip to be activated in the programmable &#34;read only&#34; memory 21. The nine outputs of demultiplexer 344 combine to form the chip selector outputs 157. 
     Finally, regulated power supply 35 encompasses state of the art techniques for converting 110 volt AC 60 cycle electromotive energy into direct current sources with voltages of -12, -10, +5, +10, and +12 volts DC. These voltages are applied to all the remaining functional blocks of programmable printer 19 so as to provide the necessary voltage sources. 
     Thus what has been described is a novel apparatus and method for producing display information incorporating stored data with external data, wherein the stored data is capable of commanding the retrieval of the external data. It should be noted that although the description utilized a print mechanism for the display of the desired data, other visual enunciating devices such as cathode ray tubes, light emitting diodes, and liquid crystals could be utilized to produce the desired display of the data. 
     It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above system apparatus and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings will be interpreted as illustrative and not in a limiting sense. 
     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.