Abstract:
Spelling errors are detected through the comparison of the keyed word with previously stored words of known spelling. The operator is immediately alerted upon the detection of a lack of comparison between the keyed word and the words available in the storage for operator consideration. When the operator is notified through an alerting device of a &#34;no match&#34;, the operator may then modify the spelling of the word if it is incorrect or accept the word if it is correct but not found in the dictionary storage. Words previously not located in the dictionary storage are then stored in a random access memory for subsequent use and the word most recently verified as correct and stored in the random access memory may be maintained at the top of a stack while the most infrequently used words will eventually be removed from the random access memory as the memory fills and overflows.

Description:
This application is a continuation of application Ser. No. 734,930, filed May 16, 1985, by Roderick S. Heard et al, titled Spelling Verification Method for a Typewriter and Typewriter Embodying Said Method, now abandoned, which is a continuation of application Ser. No. 393,836, filed June 30, 1982, by Roderick S. Heard et al, titled Spelling Verification Method for a Typewriter and Typewriter Embodying Said Method, now abandoned. 
    
    
     CROSS REFERENCES TO RELATED PATENTS AND APPLICATIONS 
     Applications having related subject matter include: 
     U.S. Pat. No. 3,995,254 to Walter S. Rosenbaum, filed July 16, 1975, issued Nov. 30, 1976, entitled &#34;Digital Reference Matrix For Word Verification&#34;. 
     U.S. Pat. No. 4,342,085, filed Jan. 8, 1979, issued July 27, 1982, Glickman, et al, entitled &#34;Stem Processing For Data Reduction In A Dictionary Storage File&#34;. 
     U.S. Pat. No. 4,503,514, filed Dec. 29, 1981, issued Mar. 5, 1985, Robert Urquhart, entitled &#34;Compact High Speed Array For Dictionary Storage And Lookup&#34;. 
     The above applications and patents are commonly assigned with this application. 
     U.S. Pat. No. 4,136,395 to Robert A. Kolpek, et al, filed Dec. 28, 1976, issued Jan. 23, 1979, entitled &#34;System For Automatically Proofreading A Document&#34;. 
     BACKGROUND OF THE INVENTION 
     With the increased use of word processing and electronic typewriting, the age old problem of detecting and correcting typographical or spelling errors in text being keyed into the word processing or typing devices can be more efficiently handled with the increased capability of electronics. The correcting of spelling errors necessitates delays, retyping and corrections and hinders timely completion of typing and word processing work. 
     Spelling verification features, programs and capabilities or systems known as dictionaries for spelling verification are available on computer systems which are typically used in a word processing environment and on dedicated word processing systems. The number of words stored in a particular data base or dictionary vary in size with the design of the particular system. In many cases, the vocabulary or the dictionary contents are fixed by the provider of the system or the program while, in some cases, the operator may supplement the system with designated words of a particular importance to that operator. 
     For example, a medical typist would have need for medically related terms in the dictionary while an engineer or scientist would use technical terms of a different nature and would find medical terms of no use. 
     Words of highly repetitive use or of a particularly troublesome nature can be selectively stored by the operator as part of the spelling verification systems used on word processing devices. 
     The prior art systems compare the word typed and stored in the memory with the words of the dictionary or the vocabulary to determine whether a compare exists in the dictionary. This comparison is typically performed on each and every word in the document after the document has been completely typed and the spelling verification routine has either been accessed or loaded into the word processing system and the spelling verification routine commanded. The comparison continues until the document has been completely compared on a word for word basis and then the words of questionable spelling are displayed or highlighted. Any word which cannot be verified by a comparison in the dictionary is indicated as a questionable spelling though highlighting or underscoring or other visual attention securing technique to allow the operator to determine whether the word is properly or improperly stored. After the operator has had the opportunity to review the questionable spellings, the operator may indicate that a word is properly spelled and no further action will be taken or the operator may indicate by rekeying that a word is improperly spelled at which point correction will occur and the comparison may, if desired, be accomplished again. 
     The technique in general described above is available on personal computers which are capable of being programmed to handle word processing tasks and which are provided with programs which perform the spelling verification checks on documents stored in the storage of the personal computer. In addition, word processing systems such as the IBM Displaywriter manufactured and sold by the IBM Corporation has available a spelling verification feature which compares the words stored in the text memory of the IBM Displaywriter with a fixed vocabulary in excess of 50,000 words. 
     Additional unique operator selected words may be stored for comparison if desired. 
     Typewriters by their very nature of printing the document as the keys are depressed by the operator do not provide an opportunity to review the entire document and to, through highlighting or other visual indication, indicate potentially misspelled words for the operator. Typewriters also don&#39;t have loading capability for loading supplemental dictionary and thus fixed dictionaries would be the only dictionary available on a traditional typewriter without magnetic media. 
     OBJECTS OF THE INVENTION 
     It is an object of the invention to provide for spelling verification on a typewriter. 
     It is another object of the invention to update the stored vocabulary in the dictionary in a variable storage as the operator keyboards the input to the typewriter. 
     It is another object of the invention to retain in the most easily accessible portion and most rapidly accessed segment of the operator controllable dictionary memory the most repetitively used words. 
     It is still another object of the invention to provide an interactive concurrent feedback to the operator indicating a non-match condition so that the operator may consider correcting the word while still on the same typing line or within a reasonably easily accessible displacement from the word being verified. 
     SUMMARY OF THE INVENTION 
     As words are keyboarded into a typewriter having an electronic processor for spelling verification and an electronic keyboard portion of a typewriter and a space bar code or other word ending indication is generated through a space bar or punctuation key or some other designated key being depressed, the compare operation then proceeds with respect to the immediately foregoing word. With two segments of memory available for the storage of words for spelling verification purposes, it is possible to have one provided with a fixed predefined vocabulary and one memory capable of receiving variable information as inputted from the keyboard. As the compare operation proceeds, it will search the fixed portion of the memory and if no word of the same spelling is found stored therein, then the variable portion of the vocabulary will be searched. 
     If a match in either segment of the memory is found, then the spelling of the word has been verified and the processor in control of the typewriter will cause no other externally detectable effects. However, internally the word, if found in the variable portion of the vocabulary, may be deleted from the variable memory and restored therein such that it will then reside at the top of the stack as the most recently utilized and verified word. Alternatively, a word found in the variable portion of the vocabulary may be moved only part way toward the beginning of the file memory and thus not congest the beginning of the file with highly specialized words. Also, initial insertion of new words may be other than at the top of the file. 
     If a no match condition exists with respect to the last complete word keyboarded by the operator, an alerting signal such as a light, buzzer or bell is activated to indicate to the operator that the spelling of the preceding word is at least questionable. If the operator detects upon review of the word that an error exists, the operator may then proceed to correct the error prior to further typing. If the operator corrects the word, the word is then recompared with the vocabulary upon the depression of the space bar or other word delimiter. If the spelling is now accepted by the operator as correct, the correctly spelled word is inserted into the variable portion of the vocabulary if it does not reside in the fixed portion. 
     If the operator detects that no error of spelling exists but rather a situation where the word keyed is not found in either of the portions of the vocabulary memory, the operator will continue to type accepting the spelling on the page. When the next word ending occurs, the preceding word having been considered will then be considered as a valid spelling and will be stored in the variable portion of the vocabulary storage. If the variable portion of the vocabulary storage is full and no further available space can be found, the word may be stored and the word which has resided in the variable portion of the memory and not been used in a spelling verification for the longest period of time may be deleted from the memory. 
     An alternative embodiment would cause an indicator to signal dictionary full and the word would not be stored. 
    
    
     DRAWING 
     FIG. 1 illustrates a typewriter having a processor for controlling the printing functions and character selection as well as a keyboard processor and a separate spelling verification processor for handling the spelling verification chores. 
     FIG. 2 is a representation of the spelling verification processor together with the associated memory available to it which includes within that memory the present word register, prior word register, main and supplemental dictionaries and operational code. 
     FIGS. 3a and 3b are the flow diagrams illustrating the functional sequence that occurs as keyboarded characters are provided from the keyboard to the spelling verification processor and the printer processor. 
     FIG. 4 illustrates the routine flow for cascading stored words downward in the memory and inserting the most recently compared word in the highest position in the memory if found in the supplemental dictionary. 
     FIG. 5 is an expansion of the routine of block 120 in FIG. 3b. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     This invention is implemented in an electronic typewriter 10 which has electronically associated with it a keyboard electronics with a channel of communication between the keyboard 14 and the keyboard electronics 12. Keyboard electronics 12 will provide output signals and may receive feedback signals from the printer processor 15. Tapped into the lines interconnecting keyboard electronics 12 and the printer processor 15 is a connection to the spelling verification processor 16. Spelling verification processor 16 also provides a command line to the indicator panel 18. Printer processor 15 provides a two-way communication path between the processor 15 and the printer portion 20 of the typewriter 10. 
     The connection of the spelling verification processor 16 may be moved with only minor modification to a point between the printer processor 15 and the typewriter 10. The changes would involve the coded data available to the spelling verification processor 16 in that the printer processor 15 outputs signals representing characters in a different form from the keyboard processor output signals. These connections only need to intercept the data flow at any point between the keyboard 14 and printer 20. 
     Referring to FIG. 2, the spelling verification processor 16 has associated with it a memory 22. The memory 22 is divided into several segments. The segments which are directly related to the spelling verification capability include the present word register 24, the prior word register 26, the main dictionary 28, supplemental dictionary 30 and the code segment 32. The present word register 24 is the register in which letters and character codes are accumulated as keyboarded by the operator on the keyboard 14 and processed by the keyboard processor 12. The prior word register 26 contains the delimited character string defined as the prior word and is a temporary storage location. 
     The main dictionary 28 is a segment of memory 22 which is loaded with the code representing approximately 50,000 words. The vocabulary stored in the main dictionary 28 is stored in a fixed menner and, therefore, is not subject to change by operator action. 
     The supplemental dictionary 30 is a segment of memory 22 available for the temporary and operator-controlled storage of words which are not found in the main dictionary 28. 
     Code section 32 is the portion of the memory 22 dedicated to the storage of the operational codes and required data storage area, such as, by way of example, those contained in Appendix A which control the function of the spelling verification processor and the movement of information and data into and out of the other memory sections as well as the operation of the indicators on the indicator panel 18. 
     Referring to FIG. 3, the flow diagram illustrates the operation of the spelling verification feature on an electronic typewriter. The other features and operations of the electronic typewriter are not illustrated inasmuch as they are not part of this invention and they only provide a basis upon which the spelling verification feature is added to improve the typewriter. 
     DESCRIPTION OF THE INVENTION 
     With the initiating of machine operation in the conventional manner by turning on typewriter 10, the spelling verification processor 16 will initialize with a standard power on reset sequence and, at the same time, will clear all of the registers or software buffers in the processor which may contain flags or indicators from a previous machine operation (block 100). 
     After the initialization routine (block 100), the spelling verification processor 16 will then determine by checking the different switches to determine which of the options have been selected by the operator. 
     The operator may turn the spelling verification feature on or off and assuming that the operator elects to have the feature on, may elect further to automatically update the supplementary dictionary 30 or the operator may update the supplemental dictionary 30 on a word-by-word selective basis. Further, the operator may delete words from the supplemental dictionary 30 should it be desirable to remove a word which may have inadvertently been placed in the supplemental dictionary 30 and proven later to be erroneously spelled. Additionally, the operator may command that all words in the supplemental dictionary be printed. 
     Upon the completion of the reading of the option switches which may take the form of physical switches or may take the form of electronic commands which have been keyed into the keyboard such as the depression of the code key plus a character key, the routine flows from block 102 to the read keyboard input routine in block 104. In the read keyboard input routine in block 104, the keyboard output is converted to a code which may be used by the spelling verification processor 16 for its purposes. 
     Upon the completion of the read keyboard input (block 104) and if the option of displaying or deleting from the supplemental dictionary 30 has been selected, the flow will be to block 106 where the decision is made as to whether the keyboard input is a request to display the contents of the supplemental dictionary 30. Otherwise, the flow is to block 114 as described below. In the event that the request is to display the contents, then the &#34;YES&#34; branch flows to block 108 and initiates a typing action to type out on display all words contained in the supplemental dictionary and the flow then branches back to above block 104. 
     If the keyboard input is not a request to display the contents of supplemental dictionary 30, the flow through the &#34;NO&#34; path will be to block 110 where a decision will be made as to whether the request is to delete a word from the supplemental dictionary 30. If the request is to delete a word from the supplemental dictionary 30, the flow will be to the routine in block 112 where a fully delimited character string is collected and the deletion of that identical character string from the supplemental dictionary is accomplished. Thereupon, the flow will return to block 104 for further reading of the keyboard inputs. 
     If the last decision regarding whether the keyboard input is a request to delete a word from the supplemental dictionary 30 (block 110) is in fact no, then the decision is made in block 114 as to whether the character is a word delimiter which would then define the end of a complete word. If the character is not in the set of codes designated as word delimiters, which by definition follow and precede a complete word, then that character is added to the present word buffer in block 116 and the flow returns to just prior to block 104 and further keyboard inputs are read. 
     If the keyboard input which is read in block 104 is not a request to either display the contents of supplemental dictionary 30 or to delete a word from the supplemental dictionary 30 as in blocks 106 or 110, respectively, and the character is a word delimiter, then the flow is directed to block 118 where a determination is made as to whether the non-match indicator is set from the previous word and is the automatic update option on or has the update request been typed by the operator. 
     If the non-match indicator for the previous word is set (block 118), this indicates that the previous word was not found in either the main or supplemental dictionaries 28, 30 and assuming one form or another of the update has been actuated, then the previous word is added to the supplemental dictionary 30 (block 120). If either the non-match indicator is not set indicating that a match was found for the previous word or the update options have not been activated or turned on, then the flow continues and the present word is compared with contents of the dictionaries in a two-step search where the supplemental dictionary 30 of specially added words is searched and then the main dictionary 28 of the most commonly used words is searched. This occurs in blocks 122 and 123. If the word is found in either dictionary 28, 30, then in accordance with the flow to block 124, there is an indication that the word matches. This may be accomplished in a multitude of ways, such as suppressing any alarms or turning off any word in error light which may have been previously illuminated for the preceding word. 
     If the word is not found in either the main dictionary or the supplemental dictionary (block 122), the &#34;NO&#34; path of the flow will lead to block 126 where a decision is made and a routine executed to indicate that the word failed to match any word in the two dictionaries 28, 30. At that time, the indicators are activated to indicate a non-match condition or word not found condition such as turning on a light or sounding an audible alarm. The form of the operator attention-getting alarm whether visual or audio is immaterial with respect to the implementation of the invention. The important part is that some attention-getting mechanism be activated to cause the operator to recognize the fact that the present word has not been found in the dictionary and needs operator verification for correct spelling. 
     The indicator 18 may also have an &#34;error in line&#34; light so that the operator is aware of an error if the next word is keyed and delimited before the word error is detected by the operator. In such case, it may be desirable to modify the routine to only update the supplemental dictionary with new words upon a carrier return command or line ending command. 
     In addition, in block 126 a flag or an indicator is set indicating that the word failed to match, and this indicator is then checked in decision block 118 upon the next pass through the flow. In this way, the contents of the word in the prior word buffer 26 at that time will be transmitted into and stored in the supplemental dictionary 30 if the operator has elected to either automatically update the supplemental dictionary 30 or has indicated by keyboard input that the word is to be used as an update on a selective basis for the supplemental dictionary 30. 
     Referring to FIG. 4, the routine illustrated therein allows a word which has been found in the supplemental dictionary to be maintained at or near the top of the supplemental dictionary while less frequently used words are shifted to the bottom and thus are available for automatic elimination from the supplemental dictionary. Other entry points may be used and the word may be moved toward other locations if desired. 
     The routine illustrated in FIG. 4 is a result of branching from block 122 in FIG. 3b wherein the decision was made that the word was, in fact, found in the supplemental dictionary. Upon such a determination, the word location in the supplemental dictionary is determined and noted. If that location is designated as location X wherein X is between 1 and N, N being the largest number of word storage positions available in the memory, and 1 being the most recently stored word location, then the word stored in position X-1 is moved to location X and a similar shifting of each word above the X-1 position is accomplished to cascade the words in storage downward leaving the location 1 available. This procedure is illustrated in block 140. 
     Upon the completion of the cascading of the previously stored word downward, the word in the present word buffer is then stored in supplemental memory location 1 (block 142). 
     Thereupon, the flow returns to block 124 at point B as illustrated in FIG. 3b. 
     FIG. 5 illustrates a further amplification of block 120, in order to add words to the supplemental dictionary when the supplemental dictionary is full, it is necessary to remove a word from the supplemental dictionary and to replace it with the new word. When adding a word to the supplemental dictionary, it is desirable to add it at the top of the stack and to cascade words previously stored in the supplemental dictionary down by one word storage location such that the least recently used word is removed from the supplemental dictionary 30 and eliminated entirely from the system when the supplemental dictionary is full. 
     In block 150, J, a temporary counter value is assigned to the word position N-1 where N is the maximum number of words contained in the supplemental register. 
     With the word in storage location N-1 now designated as word J, word J is now moved to word J+1 position in block 152. Thereupon, J is decremented by one in block 154 and the procedure repeated until all words have been cascaded downward by one storage position. At which point, then J will be equal to zero in bock 156 and the procedure branches such that the word in the prior word buffer is moved, in block 158, to word storage position 1 in the supplemental dictionary. 
     The routine in FIG. 4 when used with the routine in FIG. 5 has the effect of deleting the least frequently used word and storing the most recently used word on the top of the stack to insure maximum retention of frequently used words. 
     The techniques with which the characters and words, word stems, prefixes and suffixes are stored in the code and accessed by the spelling verification microprocessor are not key elements of this invention and have been substantially implemented in the IBM Displaywriter which is available for purchase from the IBM Corporation, Armonk, N.Y. 
     The IBM Displaywriter performs the functions and comparisons on a strictly batch processing basis after the entire document has been stored in memory and a separate spelling verification program loaded and operated with respect to that particular document. 
     The above-disclosed device is an improvement thereon which allows the implementation of spelling verification system in an interactive mode on a typewriter such that the operator gets immediate feedback and the opportunity to correct errors immediately without waiting until the entire document is completely typed. 
     It is impractical from a typewriter operator standpoint to wait for the entire document to be recorded inasmuch as some electronic typewriters have very limited text memory and, therefore, the text would not be available for playout after correction. 
     This system may be implemented by programming code using an Intel 8086 or Intel 8088 microprocessor. Both of the Intel 8086 and 8088 microprocessors are capable of handling the same code generally and, therefore, in that respect are interchangeable. 
     The implementation of this system will, of course, depend to a great extent upon what processor is selected by the implementer and it should not be considered that the Intel 8086/8088 microprocessors are the only microprocessors which would be useable in this implementation. By way of example only, important portions of the microprocessor code listing together with locations of storage, code, nmemonics, labels and comments are included in Appendix A and are appended hereto only by way of example. An implementer choosing to implement this system may quite simply utilize a different code listing or a different sequence of steps as may be advantageous under the circumstances. Those subroutines not included in the Appendix A may be coded by a skilled programmer based upon the flow diagrams in FIGS. 3a, 3b, 4 and 5. 
     Code listings for the general operation of the typewriter which are not a part of the invention are not attached. 
     Useable electronic typewriters are available on the market. For example, IBM Model 50, IBM Model 60 and IBM Model 75 Electronic Typewriters may be utilized together with a spelling verification processor to add this function thereto if so desired. 
     Should other typewriters be utilized, it will be necessary for the implementer to modify some of the techniques to accommodate the basic hardware or software features upon which the feature will be implemented. ##SPC1##