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Reference ManualFlow Charting and Block Diagramming Techniques

IBM Reference ManualFlow Charting and Block Diagramming Techniques

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ContentsINTRODUCTION 5FLOW CHARTING 5Direction of Flow 5Document Symbols 6Data Flow Charts 9Clerical Function Symbol 9Unit Record Machine Symbols 9Data Processing System Symbols 11Operational Flow Charts 14BLOCK DIAGRAMMING 18Block Diagramming Symbols, Stored-Wired Program 19RAMAC® Block Diagramming Techniques 20Block Diagramming Symbols, Stored Program 22Stored Program Block Diagramming Techniques 24IllustrationsFigure 1. IBM Charting and Diagramming Template 4Figure 2. Direction of Flow 5Figure 3. Document Symbols 6Figure 4. Variations in the Use of Document Symbols 7Figure 5. Document File Symbols 9Figure 6. Data Flow Chart 8Figure 7. Clerical Function Symbol 9Figure 8. Unit Record Machine Symbols 9Figure 9. Typical Unit Record Machine Operations 10Figure 10. Data Processing System Symbols 11Figure 11. Typical Data Processing System Configurations 12Figure 12. Typical Auxiliary Machine Operations 14Figure 13. Operational Flow Chart (Formal) , Unit Record Procedures 15Figure 14. Operational Flow Chart (Formal) , IBM 705 Procedures 16Figure 15. Operational Flow Chart (Informal) , RAMAC 305 Procedures.. 17Figure 16. Operational Flow Chart (Informal) , IBM 650 Procedures 18Figure 17. Block Diagramming Symbols, Stored-Wired Program 19Figure 18. RAMAC Decision Symbols 20Figure 19. Detailed Block Diagram, Stored-Wired Program (RAMAC 305) 21Figure 20. Block Diagramming Symbols, Stored Program 22Figure 21. Decision Symbols Uses and Shorthand Notation 23Figure 22. General Block Diagram, Stored Program System 25Figure 23. Detailed Block Diagram, Stored Program System 26Figure 24. Priority Routine Entry and Exit Symbols 27

g0tA V < z>Figure 1. IBM Charting and Diagramming Template, Form X24-5884-6

Flow Charting and Block Diagra mmin g TechniquesIntroductionThe old cliche which so strongly points up the quantitativerelationship between words and pictures hasparticular truth in the development and documentationof data processing methods and procedures. Thesystems analyst finds use for many types of pictorialrepresentations, including forms layouts, control paneldiagrams, manpower loading charts, etc. The two tobe discussed here are the work-flow chart and the blockdiagram.A work-flow chart (or simply flow chart) is definedas a graphic representation of the system in whichdata provided by a source document is converted tofinal documents. (It should be noted here that in itsbroadest meaning a document is "any instrumentconveying information," Such a definition is used inthis discussion in order to include punched cards,magnetic tape and paper tape in the same categoryas printed forms.) A flow chart, then, provides apicture of the data processing application from thestandpoint of what is to be accomplished. Such apicture gives primary emphasis to the documents involvedand secondary emphasis to the work stationsthrough which they pass.A block diagram is defined as a graphic representationof the procedures by which data is processedwithin a system. In this picture the emphasis is onthe operations and decisions necessary to complete theprocess.To put it another way, a flow chart serves to showwhat job is to be done, while a block diagram showshow a job is done. This interpretation is derived fromthe fact that flow charts are frequently composedsolely of symbols representing the form in which dataappears at various stages in a process. The actual operationswhich must be performed are indicated onlybriefly or not at all.In order to encourage standardization in the useof symbols, thereby simplifying the problem of interchanginginformation between IBM and its customers,IBM has made available the Charting and DiagrammingTemplate shown in Figure 1. The cutoutscan be used to draw symbols representing clericalfunctions, unit record machines and functions, dataprocessing systems and functions, and various typesof documents.In the pages that follow, the standard symbols usedin flow charts and block diagrams will be described.When preparing charts and diagrams for publicationor presentation, it is common practice to introducemore artistic variations of the symbols. One frequentvariation is the use of photographic reductions representingthe actual forms and machines used in aprocedure.Flow ChartingDirection of FlowThe basic element of the flow chart (and the blockdiagram as well) is the line and arrow (Figure 2)indicating DIRECTION OF FLOW (y, z)*. In order for onesymbol to have a meaningful relationship to othersymbols in a chart it is necessary that it be connectedto one or more other symbols in such a way as toindicate the sequence in which the operations occuror the disposition of the documents.*Letters in parentheses following the name of a symbol refer tothe location of the symbol on the template as illustrated inFigure 1.A11Figure 2. Direction of FlowIn flow charting, solid lines are normally used, butoccasionally it is desirable to differentiate between thephysical movement of work and the mere transfer ofinformation. This can be done by using solid linesin the first case and dotted lines in the second. Forexample, dotted lines are used to illustrate accountingcontrol functions.Flow charts are constructed to conform to the naturaltendency to read from left to right, top to bottom,5

Transmittal TapePunched CardReport Paper Tape Magnetic TapeFigure $. Document Symbolsthough variations are sometimes desirable in order toachieve symmetry and to emphasize certain points.Within this framework, flow lines can be drawnhorizontally, vertically and diagonally. The primaryconsiderations are neatness and uniformity.Document SymbolsThe various types of documents encountered in dataprocessing applications are represented by the symbolsshown in Figure 3. Two sizes of each are provided.Normally, a single diagram will use either the smallor the large symbols but not both.The SOURCE DOCUMENT (c, k) symbol indicates anypaper document from which information is extractedduring a process. The REPORT (w, x) symbol, on theother hand, indicates a paper document preparedduring a process. When a document serves both purposes(e.g., a permanent ledger card to which informationis posted) , the source document symbol is used.The TRANSMITTAL FORM and PAPER TAPE (1, r plus s)symbols are constructed from the same cutouts. Indrawing the large transmittal form, that portion ofcutout "r" marked off by arrows provides the topand sides of the form, and cutout "s", the bottom. (Thetwo "folds" of the paper tape are obtained from thetransmittal form symbol by rotating the template180°. A short diagonal line connecting the lowercorners of the two halves gives the illusion of a foldedstrip of tape.) The transmittal form normally representsan adding machine tape or some other type ofbatch control sheet accompanying other forms.The two remaining document symbols are thePUNCHED CARD (g, o) and MAGNETIC TAPE (f, n) symbols.When document symbols appear in a flow chart,the symbols are usually labeled to indicate the type ofinformation contained therein. Frequently, the typeof form is further indicated by drawing the generaloutline of the form. Figure 4 shows several ways inwhich this can be done. Included are ways in which6

InvoiceTimeCard1-111 1., wDateHrs.PayrolChangeAuth.I nventory LedgerOrders!Status I 1TimeManyCashReportLaborDist.!DeductionListPayrol IJournalMulti -part Split AssociatedForm Form ReportsIll II 11 III I 1 I II1 I I II IIII I6.> 2 0c 0 a.dẒ , QtyAmtStub Card51-ColumnCardPay to $Card DeckCard Check-ManyIBatchCtr'livMagneti cTape-729 IVMulti-reelTape FileFigure 4. Variations in the Use of Document Symbols7

IBIS[ M DIAGRAMMING AND CHARTING WORKSHEETForm X24 6413-0Printed U. 5. A.ApplicationProcedureTypical Appl icationDateDrawnBy NAPPage 1 of 1TransactionDocumentNNBatchControlTotalsTransaction Card...-- ...- ..,-"'.--..- ,..-...- ..--"IN" Register."""*"......_XXNN NN',..'N..Control Sheet..--`-'–'-'-- 7Ledger Filel'.>TrialBalance'... N41/4,XX /ins •x Xbal.xxI' AJ1IStatusReportsI"OUT",RegisterII XX//-.../////Control SheetIt.xx XX...-------.---- 7/ 1IAnalysis File1Maly isReportx..:-////////////////5.WFigure 6. Data Flow Chart8

C(Payroll Clerk )Clerical Function Position Title(3alance andCPosition 12 )Operation DescribedPosition CodeFigure 7. Clerical Function SymbolTwo-DrawerFileFigure 5. Document File SymbolsFour-DrawerFilethe impression of many documents or multiple formscan be given, various special types of punched cardsrepresented, and paper and magnetic tape identifiedas to type.In addition to the documents themselves, it is alsonecessary to represent files of documents. This is donewith the FILE (q plus r) symbol shown in Figure 5.Data Flow ChartsThe symbols introduced thus far are all that are requiredto draw one simple type of chart — the dataflow chart, so called because it describes an applicationin terms of the development of information.Figure 6 is a data flow chart representing a portionof a punched card accounting application. A chart ofthis type might be used in depicting the overall applicationfor management or for persons receiving thefinal reports. The source of the information is readilyseen, the cards used in the procedures are evident,and the various reports relating to the job are shown.In addition, the manner in which control is establishedand maintained throughout the process is shownby the use of dotted lines and a symbolic representationof control totals (XX) on the various reports.To anyone even vaguely familiar with punchedcard accounting, it is obvious that a card punch, anaccounting machine and, perhaps, a sorter or collatorare involved in the procedures. Actually, as will beshown later, all of these machines, plus a card verifier,interpreter and reproducer, are required. A secondtype of flow chart which provides this informationwill be described.Clerical Function SymbolOperations performed at a clerical work station arerepresented by the CLERICAL FUNCTION (u) symbolshown in Figure 7 along with various ways in whichthe operation can be indicated. Specifying only aposition title or code implies that a job descriptionfound elsewhere will provide the necessary informationas to exactly what occurs at that station.Unit Record Machine SymbolsFigure 8 illustrates the four basic symbols used to depictunit record machine operations. A few of themany ways in which these symbols are used appearin Figure 9.The CARD PUNCH and CARD VERIFIER (m) symbol indicatescard preparation and verification by key-drivendevices (including machine types 10, 24, 26, 27, 28,56) . The Card Proof Machine generates an addingmachine tape which is represented by the TransmittalForm (Figure 3) .C)Card Punch,Card Verifier,and Other Key-Driven DevicesAuxiliaryMachinesFigure 8. Unit Record Machine SymbolsSorter andCol latorAccountingMachines9

V(Cord ProofPunchNX 80X 80DetailedList ---- ReportGroupPrint—SummaryReportFigure 9. Typical Unit Record Machine Operations10

The same symbol is also used to represent otherkey-driven devices such as the Cardatype®, TypewriterCard Punch, and Typewriter Tape Punch.The SORTER and COLLATOR (a) symbol, representingoperations of machine types 82, 83, 85, 87, 88, 101and 108, may have one or more card files leading tothe operation symbol and one or more card files leavingthe symbol, depending on the type of operationbeing performed.The ACCOUNTING MACHINE (t) symbol is usually associatedwith a Report symbol (Figure 3) illustratingthe result of the operation. One of the examplesin Figure 9 shows how printing with summary punchingis illustrated.The AUXILIARY MACHINE (b) symbol is used to representoperations performed on reproducing andsummary punches, interpreters, calculators, facsimileposting machines, and tape-to-card and card-to-tapepunches.In Figure 9 it should be noted that documents producedas a result of an operation have a line leadingto them but no arrow. This is done to indicate thatthe symbol does not represent a separate job stepbut is associated with the symbol to which it is connected.The line leading from the document to thenext job step in which it is involved does have anarrow.Data Processing System SymbolsThe symbols in Figure 10 are used in flow chartingto illustrate data processing system operations. Thelarge number of machine components of a dataprocessing system requires a somewhat different typeof symbolism from that used with unit record machines.In this case the rectangle labeled CENTRALPROCESSING UNIT (c) in Figure 10 is used to representthe basic system components. This is assumed to includethe main storage facilities, the arithmetic unit,CentralProcessingUnitAuxiliaryMachine(Off-Line)Input/Outpui\,ControlAuxiliaryDrumStorageInquiryAuxi I iary StationDisk StorageCard Reader orCard PunchPaper TapeReader or Punch PrinterTypewriterFigure 10. Data Processing System Symbols11

A2CDFigure 11, Typical Data Processing System Configurations12

and the basic controls. To this are connected additionalsymbols representing peripheral componentsand the documents which they process. For example,a reel of magnetic tape indicates that a magnetictape unit is connected; a punched card with an arrowleading to the CPU indicates a card reader; a punchedcard with an arrow leading from the CPU, a cardpunch; and so on.In some applications the manner in which auxiliarystorage units are used (e.g., magnetic drum storageon a 705 system or magnetic disk storage on a 650system) is an important feature of the system. TheAUXILIARY DISK STORAGE and AUXILIARY DRUM STORAGE(m) symbols, connected to the central processing unitby a two-pointed arrow, provide a means of illustratingsuch features.For many data processing systems, the INPUT-OUTPUTCONTROLS (r) must be shown in order to depict clearlythe system's capabilities. A specific example is the IBM7070 with the 7604 Tape Control. The manner inwhich magnetic tape units are assigned to the twodata channels is a significant factor in the data processingprocedure in that processing time will dependpartly on the assignment. The same thing is true inthe case of the 705 III or 709 with two or more DataSynchronizers and the 705 I and II with two or moreTape Record Coordinators.With some other systems — a 705 II with 754 TapeControls, for example — the manner in which themagnetic tape units attach to the central processingunit has no obvious effect on the application approachor timing, hence the tape controls need not be shown.Figure 11 illustrates typical ways in which dataprocessing system operations are flow-charted. TheCentral Processing Unit symbol is sometimes labeledwith the type number to identify the system. Whenno confusion as to the system type can exist, the spacecan be used to identify the processing step.The illustrations in Figure 11 can represent any ofthe following system configurations:A. Card reader, card punch and printer providingdirect input and output to:1. an IBM 3052. an IBM 650 Data Processing System3. any IBM 700 series system4. an IBM 7070 Data Processing SystemB. Four magnetic tape units operating with:1. an IBM 650 Data Processing System2. an IBM 705 Data Processing System with oneor more 754 Tape Controls or one 777 Tape RecordCoordinator3. an IBM 705 III Data Processing System withone 767 Data Synchronizer4. an IBM 704 Data Processing System with 753Tape Civiitrvi5. an IBM 709 Data Processing System with one766 Data SynchronizerC. Four magnetic tape units, auxiliary drum storage,a card reader and a printer operating with:1. an IBM 705 Data Processing System with oneor more 754 Tape Controls or one 777 Tape RecordCoordinator2. an IBM 705 III Data Processing System withone 767 Data Synchronizer3. an IBM 704 Data Processing System with 753Tape Control4. an IBM 709 Data Processing System with one766 Data SynchronizerD. Five magnetic tape units operating with:1. an IBM 705 Data Processing System with two777 Tape Record Coordinators2. an IBM 705 III Data Processing System withtwo 767 Data Synchronizers3. an IBM 709 Data Processing System with two766 Data Synchronizers4. an IBM 7070 Data Processing System with7604 Tape Control5. an IBM 7090 Data Processing System withtwo 7607 Data ChannelsE. An IBM 7070 Data Processing System with 7604Tape Control, five 729 IV Magnetic Tape Units,four 729 II Magnetic Tape Units, 7300 DiskStorage, 7500 Card Reader, 7150 Console ControlUnit (typewriter) , 7400 Printer, 7550 CardPunch and 7900 Inquiry Station. (The remotelocation of the inquiry station is indicated bythe broken line.)13

Card-to-Tape Operationsi>oor722orTape-to-Card OperationsOrTape-to-Printer OperationsFigure 12. Typical Auxiliary Machine OperationsThe AUXILIARY MACHINE (b) symbol in Figure 10 isused to identify the units involved in off-line operations.Figure 12 shows a simplified symbolic representationfor card-to-tape, tape-to-card, and tape-toprinteroperations as well as variations in which thespecific units are identified by type number.Operational Flow ChartsThe operational flow chart is an extension of the dataflow chart in that it shows the job steps involved inthe development of information as well as the documentsthemselves. Figure 13 is an operational flowchart representing the first few steps in the punchedcard application illustrated by the data flow chart inFigure 6. The manner of presentation in this examplemight be categorized as "formal" in that the basicflow charting rules have been closely followed.Note that the primary direction of flow of the applicationis in a vertical line from the top of the pageto the bottom. Secondary functions (e.g., balancingoriginal control totals against totals developed elsewherein the procedures and filing cards prepared forlater processing) are shown to one side.The information provided by Figure 13 is sufficientto satisfy the needs of all but the person responsiblefor installing and maintaining the system and theclerks and operators performing the various clericaland machine functions. In the case of punched cardand clerical procedures the latter requirements can besatisfied by providing:1. a narrative description of the manual operationsto be performed at each point in the procedures2. control panel wiring diagram, carriage controltapes, etc., for each machine function whichrequires them.This material, assembled in a notebook or file foldertogether with forms layouts, job schedules, and so on,comprises a manual of procedures. The circled numbersat each work station or job step symbol providea simple means of referencing such material to theflow chart.14

hForm X24-6413-0IBM DIAGRAMMING AND CHARTING WORKSHEETPrtnied U. 5. A.Application Typical Application Date PageL of _2_Procedure Procedure A Drawn By NAPReceiving '''■Clerk )/ ■// 1/Add. //Transaction IMach. ,/Document ITape One Tape'1,, Per Batch0V 0I(Card Punch■..Control Sheeti i - -I 1 1V 0 i\Lir -..\ 0Balance and -\___ /e ri,y., 1`File Documents.)../A1TransactionCardV0Interpret"IN"RegisterList andBalance0-----N--J0-/------ 7Reproduce Duplicate Card —C> Ledger File /Sort0To Procedure BN \Sec.o-YP.Merge0__ -..Figure 13. Operational Flow Chart (Formal) , Unit Record Procedures15

For, X24-6413-0IB DIAGRAMMING AND CHARTING WORKSHEET• Printed U. 5. A.IBMApplication Consolidated Functions Ordinnry Life Insumnre Date Page of _1_Procedure Policy Issue Drawn By NAPNew IssueNewIssueTapeSort byPlan, Age,Policy No. ,Line No.InSortedNewIssueTapeVEdit and CheckError List-_,---AII'PolicyRecordTapeMultiplePolicyRecordTapeSort byPlan, Age,Policy No.aSorted MultiplePolicy RecordTape1 Vrti:\ RcTapeso–Policy Issue1 Error ListVPolicyConsol_FacePolicy a ;dotedISheetFace PolicyMaster.2.: Sheet Record MatTape TapeETTapeMasterMatIn..-i'Figure 14. Operational Flow Chart (Formal) , IBM 705 Procedures16

Figure 14 is an illustration of a typical operationalflow chart of an application of a data processing system— in this case the 705. This chart also falls in theformal category. Figures 15 and 16 are informal operationalflow charts illustrating the use of line drawingsand photographs in place of the template symbols.Flow charts of data processing system applicationsusually convey much less information as to what isPUNCHED. STRING, PINAND BUTTON HOLE PRICETICKETSTICKET CONVERTERIBM 305TIMELY FACTUAL MERCHANDISINGREPORTSFigure 15. Operational Flow Chart (Informal), RAMAC 305 Procedures17

Figure 16. Operational Flow Chart (Informal), IBM 650 Proceduresactually being done than a flow chart of a punchedcard procedure, because each step is considerably moreinvolved. For this reason, complete documentationof the application must include block diagrams ofeach processing step. The manner in which these areconstructed will be described in the next section.The labeling of an operational flow chart for adata processing system application is important whenit is to serve as a guide to programming and operating.It is at this point that tape and program identificationmust be introduced. Schemes have been developedwhich lead to great efficiency in systems planning andoperating, particularly with regard to:I. programming job assignments2. tape labeling and library maintenance3. job scheduling.A brief description of the highly efficient systemused at one installation can be found in the IBMGeneral Information Manual, "The IBM 705 Systemof Accounting at Southern Railway" (Form E20-6025) .Block DiagrammingA block diagram has been defined as a graphic representationof the procedure by which data is processed.Hence, one could assume that block diagrams wouldbe used to illustrate clerical, punched card machineand data processing system operations. While it istheoretically true that clerical and punched cardmachine functions can be block-diagrammed, thispractice is not followed since many of the steps areassumed to be understood by the clerk or machineoperator. Furthermore, in the case of machine operations,control panel wiring diagrams and planningcharts are more descriptive of the functions than ablock diagram would be.This discussion, then, will be concerned only withblock diagramming data processing systems functions.It might be argued that the coding sheet (or programmingform) is to the data processing systemsoperation what the wiring diagram and planningchart are to the punched card procedure. This is truein only a limited sense because the coding sheet lacksthe graphic qualities that the others have.One of the most important uses of the block diagramis to provide the programmer with a means ofvisualizing, during the developmental stages of programming,the sequence in which logical and arithmeticoperations should occur, and the relationship ofone portion of a program to another. The codingsheet does not offer this advantage.The amount of detail included in a block diagramwill vary according to the purpose it is to serve. In theearly stages of program development the primarypurpose of the diagram is to experiment with andverify the accuracy of different approaches to codingthe application. In this instance large segments ofthe program are represented by a single symbol.Once an approach has been established, a block diagramis prepared to serve as a basis for coding. At this18

point the nature of the system being programmed mustbe taken into account. For the MI 305, such a blockdiagram will usually show in detail both the storedprogram steps and the control panel functions. Forthe 650, 705, and 7070 systems, however, such detailis neither necessary nor desirable. In order to preserveits usefulness as a clear picture of the overall programlogic, the block diagram should not, in thesecases, be a replica of the coding. Because of this andother differences, block diagramming techniques forthe 305 will be discussed separately.Block Diagramming Symbols,Stored-Wired ProgramA procedure for a system which utilizes a combinationof stored and wired programming is characterized bytwo main features:1. functions initiated by control panel wiring2. functions initiated by stored program instructions.The symbols chosen for graphically illustrating suchprocedures serve to differentiate between these twotypes of functions.In order for the block diagram to fulfill its purposecertain other aspects of the program must also beshown, namely:1. the program exits which cause the change fromstored program to wired program control2. points at which signals are generated to initiateoperations on the console, punch or printer3. the condition which causes a particular branchof a program to be taken.The recommended symbols for use in block diagrammingprocedures for a system combining .thestored program and wired program concepts (as doesthe 305) are shown in Figure 17.The DIRECTION OF FLOW (y, z) symbol has the samefunction as it did in the flow chart. Since the averageblock diagram contains a large number of symbolsand follows the "top-to-bottom" rule closely, the arrowheadsare frequently omitted except where necessaryfor clarity. Dotted lines are used occasionally buthave no standard meaning.The STORED PROGRAM STEP (c, k) symbol correspondsto program instructions. In a detailed block diagrameach such symbol corresponds to a single instructionstep and the address of the drum storage locationassigned to that step is indicated at the top left cornerof the rectangle.The CONTROL PANEL FUNCTION (d, 1) symbol indicatesoperations defined by control panel wiring. Theonly time this symbol refers to other than a processcontrol panel function is when it is preceded by acommunication symbol.Direction of FlowO 0Program ExitStored Program StepControl Panel FunctionsStepConnectorFigure 17. Block Diagramming Symbols,Stored-Wired ProgramBranchIdentificationCommuni cationLineTwo sizes of each of these two symbols are providedon the template, but the appearance of a diagramis improved if different sizes of the same symbolare not intermixed.The PROGRAM EXIT (h) symbol indicates that thelast program instruction contained a control codewhich will cause an impulse to be emitted at a programexit. The specific program exit involved isindicated by placing the corresponding letter, numberor special character within the symbol. A programexit symbol will always be preceded by a storedprogram step symbol.The BRANCH IDENTIFICATION (p) symbol is used toindicate the condition which must exist for one oftwo or more alternate paths in the program to betaken. The conditions are established as a result ofa compare, a test of the accumulator or a selector, orcharacter selection. These are all process control panelfunctions, and the branch identification symbol will19

One of four single digit codes(Use as many exits as required)NormalFigure 18. RAMAC Decision Symbolstherefore always follow a control panel function symbol.The various conditions are indicated by labelingthe symbol as shown in Figure 18.The COMMUNICATION (u) symbol indicates the use ofa program exit impulse to signal the console, printeror punch over the corresponding communication line.The particular unit and line involved are indicatedby the label on the symbol. The function initiated isindicated by a control panel function symbol followingit.The STEP CONNECTOR (t) symbol, like the communicationsymbol, does not represent a specific instructionor control panel function. It is used to indicate:1. points at which a program will terminate2. the identity of the next step in the program whenthat step does not immediately follow on theblock diagram.RAMAC ® Block Diagramming TechniquesThe basic techniques for preparation of IBM RAMAC305 block diagrams are easily illustrated by an example.Figure 19 is a small part of a diagram of an inventoryand billing application. A close examination of thisexample will bring out most of the important featuresand techniques of a good block diagram:1. The main direction of flow is from the top ofthe page to the bottom.2. The starting point of the program is indicatedby an arrow labeled "copy out."3. The stored program and control panel functionsymbols are clearly labeled to indicate the operation(a single operation in the case of the detaileddiagram shown) .4. Notes have been used to indicate unusual situations(e.g., cause of stops) .5. A dotted line has been used to connect a branchpoint which actually does not exist in the program.Including this condition in the diagramprovides a positive indication that all cases havebeen considered.6. Arrowheads are drawn only when they add to theclarity of the diagram.7. Control panel function symbols for other than theprocess control panel need not have an exit.8. A step connector symbol labeled "Go to Step 00"has been used at the bottom of the page ratherthan a direction-of-flow line all the way to thetop of the page.9. The two major program segments (all that couldbe conveniently shown on a single page) areclearly separated. To avoid crowding (and theresulting confusion) , other segments have beenrelegated to subsequent pages.20

1IB DIAGRAMMING AND CHARTING WORKSHEETIBMForm X24-6413-0m Printed U S. A.ApplicationProcedureInventory and B .I " g Date Page _I— o .- _Drown By NAPCopy Out199 NitTransfer Ktow1I00Transfercard code 1to Char SelI0 CLr) ID+TestCharacterSelectorimCont.Page-Test / Test \(ThSelector1sLi_i--\ S4eiector-Cont.Page-1StopI '/Pick up \II StopSelector IDrop outI Stop Se] 3 PickI 1 Cards out ofup Sel 401ICards oLtsequenceofsequenceComp. Cust.18No. to Ord .

Block Diagramming Symbols, Stored ProgramThe block diagramming symbols used with storedprogram systems, including the 650, 705, and 7070,are shown in Figure 20. (SHARE, an organization of704, 709 and 7090 users, has published standards fortheir members.)As before, the DIRECTION OF FLOW (y, z) symbol isthe basic element of the diagram. It is the nature ofmost programs prepared for systems of this type toinvolve many decisions, that is, tests to determinewhich of two or more paths should be taken. Thisleads to complex block diagrams and hence to therequirement that flow lines be drawn with an arrowwhenever the direction is not immediately clear."Looping" in a program (that is, repeating an instructionsequence) is also a common occurrence andin some cases leads to violation of the basic rule thatdiagrams should run from the top of the page to thebottom.Direction of FlowConsole Connector or StepOperation Identificationor HaltProcessing Function0650 TableLookupFigure 20. Block Diagramming Symbols,Stored ProgramThe CONNECTOR Or STEP IDENTIFICATION (p) symbol,is used to indicate a direct connection between sectionsof a block diagram which cannot be easily connectedby arrows (i.e., sections widely separated on the pageor on different pages) . In this way it also provides anindication of and a label for, points in a programto which other portions of the program may branch.When a connector symbol refers to a point on anotherpage, the page number should be shown adjacent tothe symbol.The TABLE LOOKUP (a) symbol is used to denote aninstruction sequence based on the TLU function of theIBM 650. Since the LE, LL and LEH functions ofthe 7070 cause branching, the decision function symbolis used in these cases.The CONSOLE OPERATION and HALT (t) symbol representseither a point in a program at which data isintroduced via the console typewriter or switch settings,or any point at which a program terminates — eithernormally at the completion of the job, or because ofan error condition.The PRIORITY ROUTINE IDENTIFICATION (tt, v) symbolis used in block diagramming for the IBM 7070. Thesymbol does not represent a program function, butmerely serves as a label for the routine that followsand identifies the routine as one which will be executedin the priority mode.The INPUT-OUTPUT FUNCTION (e, m) symbol 1S usedto denote any function of an input-output device.Included in this category are magnetic tape (e. g.,reading, writing, backspace, rewind, etc.) , card reader,card punch and printer functions, as well as thoseinvolving multiple-word communication between auxiliarystorage units (such as drum or disk storage)and the main storage.The PROGRAM MODIFICATION FUNCTION (d, 1) symbolis used to denote an instruction sequence which effectsa change in the stored program itself. Included are:1. address alteration or modification2. operation code modification3. setting of program switches (by above techniquesor by bit or digit manipulation, etc.)4. setting of indexing registers or words5. setting or resetting an indicator.(Each particular system provides unique ways inwhich program modification can be implemented.However, the purpose of the block diagram is toindicate the function and not the specific technique.)The DECISION FUNCTION (b, i) symbol is used to depicta point in a program at which a branch to one of twoor more alternate paths is possible. The manner inwhich the choice is made is indicated by the labeland can be based on:1. a comparison or the test of a compare indicator22

TEST CONDITIONS, LOGICAL CHOICES, DECISIONSENGLISH STATEMENTSHORTHAND STATEMENTCompare A with B (where B is the commonfactor or constant value)A is greater than BA is less than BA is equal to BA is not greater than BA is not less than BA is not equal to BCompare indicator settingsCheck indicator settingsA: BA > BA < BA=BA BA BA BBalance test results (plus, zero, minus) + 0End of fileEnd of JobProgram switch settings (No Operationand Transfer in the 705)HI LO EQON OFFEOFEOJNOP TRFigure 21. Decision Symbols Uses and Shorthand Notation(depending on the manner in which the compareoperation functions)2. a balance (sign) test3. a program switch setting4. an indexed branch instruction5. a check indicator setting, etc.The condition upon which each of the possiblepaths will be taken must be identified. In addition,all possible conditions should be accounted for. Thisis done by labeling each of the flow lines leading fromthe decision symbol as shown in Figure 21. A list ofcommonly used shorthand notations for program conditionsis also shown.23

The PROCESSING FUNCTION (C, k) symbol is mosteasily defined as that symbol used to represent a functionwhich cannot be represented by one of the othersymbols. Generally, such operations are those concernedwith the actual processing functions of theprogram. Some programs — the assignment section ofa generalized sort, for example — are concerned withthe modification of another program. The operationswhich the first program performs on the second areprocessing functions, and the processing function symbolshould be used in illustrating them. The modificationswhich the first program performs on itself,however, are program modification functions and thecorresponding symbol is used.Stored Program Block DiagrammingTechniquesEarlier in this discussion reference was made — butwithout explanation — to "detailed" and "general"block diagrams. The amount of detail presented in ablock diagram will depend upon the use that is to bemade of it. The three most important uses are:1. as an aid to program development2. as a guide to coding3. as documentation of a program.In the program development stage, the block diagramserves as a means of experimenting with variousapproaches to the mechanization of the application.At this point, logical program segments will havebeen established, at least tentatively, through flowcharting. Starting with blocks representing the majorfunctions of the proposed program, the programmerdevelops the overall logic by adding blocks to depictinput and output functions, steps for the identificationand selection of records, and decision functions.After the overall logic of the program has beententatively established, the large segments are extractedfrom the "general" block diagram and analyzed in thesame fashion. Proceeding in this manner, the blockdiagram becomes more detailed. The eventual goal isto produce a diagram which clearly shows all decisionpoints in the program and which can be used to verifythat the procedure satisfies all possible conditionswhich can arise during program execution.Once the procedure is established, and provedsound, the block diagram becomes a guide to coding.Unless the person who developed the diagram wasan experienced programmer for the data processingsystem to be used, it is almost certain that the peculiaritiesof the machine logic will necessitate changes inthe program logic. Thus, the diagram may need to beredrawn and reverified at this stage.Upon completion of the coding, testing and installingof the procedure, the program must be documentedto facilitate future modifications which arebound to become necessary. At this stage, the blockdiagram can greatly simplify the problem by serving asa "map" of the program listing or coding sheets. Tobe useful in this respect, the block diagram must berelated, by labeling, to the instruction steps.Conventions for labeling instructions and data havebeen established in connection with the several automaticprogramming systems in use (e. g., AUTOCODER,SOAP) . These same labels should be used to identifythe blocks on the diagram which correspond to theinstruction sequence on the coding sheets. The labelsare placed just above the symbol to the left of theflow line.Final documentation of a program should includeboth general and detailed block diagrams. The generalblock diagram helps in understanding the more detailedone and also provides an easily understoodpicture of the procedure for those who might beinterested in the concept only.Anyone who has seriously attempted to program adata processing system knows that a considerableamount of scratch paper is consumed before anythingresembling a finished block diagram is obtained. Forthis reason, the illustrations which accompany thistext may not resemble very closely the diagrams whichwill be found in, on and around the desk of thetypical programmer. They do, however, illustrate thegoal he should be trying to achieve in appearance.Figure 22 is a general block diagram of a consolidatedlife insurance file maintenance program.* Thisparticular diagram is arranged on the worksheet soas to show clearly the logical relationship among thethree major segments of the program. Because thediagram reads from the top of the page to the bottom,for the most part, arrowheads have been omitted exceptwhere lines join and where the direction of flowmay not be immediately obvious.*In this application ungrouped 80-character transaction records areprocessed against long, ungrouped master records. Unmatchedtransactions may be errors or represent new business and requiregeneration of a new master record. Master records may be activefor reasons other than the presence of a transaction record.24

IBM DIAGRAMMING AND CHARTING WORKSHEETForm X24-6413-0Printed U. S. A.ApplicationProcedureOrdinary Life Insurance Consolidated Functions Date Page 1 OF 1Daily File MaintenanceDrawn By NAPStart ,(Read FirsMasterRecordRead First)Transaction( Record•N o NewBusinessLOTT ; M.LO MAuto. NoChg.W iteUnmatchedTrans Rec.IGenerate NewMaster Record(Backspace)MasterTapeYes ECIIDetermine Type 1of Trans. and 1Process. Set IProgram Switches I-4Acc't Rec.SWOfffilling ReSWOffWriteAcctRecord(Write \\BillingRecordYesDetermine Type 1and Process. 1Set ProgramSwitches.-4„A ftra V .. NoDateYesPerform AnniversaCalcu- 1lotions, Set 1Program Switches0- -4(ReaTransactionRecord1DeleteSW. 1OffOnOff—hange ReSWOffOnDeleteSW. 2On/Write10-- DeletionRecord-.4ReadMasterRecordPerform BillingCal cu I ati ons-Set ProgramSwitches.IP-nOffWriteChangeRecorddWriteMasterRecord,.../Billing NoDateYes-c:ZI(Set \SW. A tOn /•'FTFigure 22. General Block Diagram, Stored Program System25

IBM DIAGRAMMING AND CHARTING WORKSHEET•Form X24 6413.0Printed U. S. A.ApplicationProcedureOrdinary Life Insurance Consolidated Functions Date Page 1 of 3Daily File Maintenance Routine Drawn By NAP0StartIRead Firs)Master( RecordRead FirstTransactionRecordill400.•LO TLO M 0Page 2 E0 Page 28JKMasterFieldChangeRoutineRegularCol lectionUnpaidRoueSetBillingOnISW)LapseCollectionUnpaidRoutineet Acc 'andChgW's OnPage 3 a)OffOnWrite(AccountingRecord ,./Set(Acct SW)OffTestransactCodRegularCol lectionPaidRoutineSetDelete SW)1 OnPolicyStatusRequestOff BillingSW.OnWriteBillingRecord23LapsCol lectionPaidRoutineAdvancePremiumPaymentRoutineAdvance4 I Premium -_>. __„WithdrawalRoutineWriteStatusRecordPage 2 0-(ReadTransactions,.‘RecordDelete OffSW. I0Set(tilling $W)OffOff*OnWrite(ChangeRecord/ SetChg. SW.Off5LoanIssueRoutineOn -,f1Set(Delete SW)1,20ffOff .0.Ontifc. .67I(SW. A )OffWriteLoanDeletionPaymentRecordRoutine Page 30(B i lli S ng e t SW)OnAccountingAdjustmentRoutineC:ReadMasterRecord•On*Off( Write masie rRecordfrFigure 23. Detailed Block Diagram, Stored Program System26

Figure 23 is part of the same procedure shown inmore detail. In this instance an arrangement whichbest utilizes the available space has been used. A diagramsuch as this one is sufficiently complete to serveas a guide in coding even though certain programfunctions are still not represented (e. g., read-writeerror routines, end-of-file and end-of-job routines) . Adetailed diagram documenting a completed programwould include all such functions.a.. /:\\ILi I I yPriorityn-- NOUT I FieTransactionTape Priority jPriorityRoutineDuring program development, the "open" arrangementof the diagram on the page, as shown in Figure22, is preferable to that used in Figure 23 not onlybecause it shows more clearly the alternate programpaths, but also because it leaves more room for insertingadditional steps. The arrangement used in Figure23 is most suitable for use in documenting the programbecause it requires less space.Block diagrams prepared for an IBM 7070 willdiffer in some respects from those illustrated becauseof the Automatic Priority Processing feature and theunique manner in which input-output functions arehandled. Since the main processing functions willusually be executed in the non-priority mode, thecorresponding block diagram will follow the patternoutlined. Priority routines, however, cannot be shownas linked directly to the non-priority routines sincethe point at which the linkage will occur is notknown. To call attention to this in the diagram thepriority routine identification symbol is always usedat the beginning of such an instruction sequence.A priority routine is terminated by the executionof a priority release instruction, the address of whichdetermines whether control will return to the pointat which the interruption occurred or to some specifiedother point. In the first case, the block diagramof the sequence should end with a dotted line andarrow from the last symbol. If control is to be transferredto a specified routine, then a solid line and aproperly labeled step connector symbol should beused. Figui e 24 illustrates the manner in which priorityroutine entry and exit points are diagrammed.ReleasePriorityFigure 24. Priority Routine Entry and Exit SymbolsReleasePriorityThe 7070 performs a number of unique operationswhich, in preparing block diagrams, should be consideredto be program modification functions. Includedin this category are:1. setting and modification of indexing words2. setting priority stacking latches3. loading the priority masking register4. establishing Halt or Sense mode for field overflowor sign changing conditions5. setting of electronic switches.Perhaps the most important aspect of systems andprocedures development is the communication of ideasbetween an analyst and... the individuals involved in current systems andprocedures... the managers responsible for the approval andimplementation of new systems and procedures... other analysts working on the same or relatedsystems and procedures.Adherence to the flow charting and block diagrammingstandards outlined in this manual will greatlyimprove the effectiveness of communication in thisendeavor.27

C20-8008-0oInternational Business Machines CorporationData Processing Division112 East Post Road, White Plains, New York