N.B. This text is taken from PDF files Vol4P2_0-4.3, Vol4P2_4.3.1-7, Vol4P2_Apps.
which are here:

                                                Volume IV


          2.1  Preparatory Work
          2.2  Post-Mortem Point Subroutine
          3.1  Tasks
          3.2  Data
          3.3  Results
          3.4  Organisation
          4.1  Tasks
          4.2  Data
          4.3  Results
          4.4  Organisation
          5.1  Tasks
          5.2  Data
          5.3  Results
          5.4  Organisation
          6.1  Method of Termination
          6.2  Off—Line Printing of Results
     7    LOG COMMENTS
                                                Amendment No. 27
6/1                                              February 1965

Section 1 1. INTRODUCTION This part of Volume IV contains detailed descriptions of the routines that form the Programme Trials System (PTS). The Routines are written on to the program tape by the Translator (see Volume III, Part 1, Section 15) and loaded into store when the program is ‘trials allocated’ (see Part 1, Section 7.4 of this volume). The P.T.S. routines occupy approximately 1500 short compartments and the Program Loading Sequence will arrange to increase the program's storage requirements by this amount before allocating the program. When trials allocated, the program will always be given a modification group; and if the installation's Master Program contains the parameter ‘print PTS results on-line at end of trial' a printer route will be allocated to the program, unless it already requires one. None of these additions will affect addresses within the program. A P.T.S. trial should not be run on a strung program, the machine code of which is followed by other Intercode or CLEO programs. P.T.S. will be placed at the end of the ‘most favourable‘ program chapter (see P.L.S. Specification, Part 1, Section 7.5) and has Master Program tag 14. The routines are written in three parts, which call each other into the store by overlay. There is also a constant part, to deal with differences between normal and ‘trials’ Master Program operations. The main P.T.S. routines use the program switch, and thus behave like an extension of the program. Those parts which are in effect extensions of the Master Program use the Master Program switch. The three parts of P.T.S, are: (1) Set-up routine: sets up on magnetic tape any trial data specified by the programmer. (2) Post-mortem routine: records on magnetic tape the contents of specified sections of the store at specified points during the trial. (3) Print routine: prints out the contents of these specified sections. On the program tape, the first of these is separated from the others by the actual trial data and dumps points, which are normally submitted with the program when it is initially translated. Any subsequent changes can be made in either of two ways: if trial data and/or dumps points are the only parts of the program to be amended, the Trials Program (08005) can be used (see Volume V, Part 3, Section 12); if other parts of the program are to be amended at the same time, an amending run of the Translator is performed. 6/9 Amendment No. 4/43 December 1968.
Section 2 2 PROCESSING CARRIED OUT BY THE INTERCODE TRANSLATOR 2.1 Preparatory Work In order that the programme trials routines may carry out their tasks, the following preparation is done by the Intercode Translator. Steps (1) and (2) are also carried out by the Trials Programme (08005). (1) A block of information for each post-mortem point is output on the programme file, after the latest computer code version of the programme. (For the layout of this block see Appendix G to Section 12, Part 3, Volume V). (2) Each file of trial data is written on the programme file after the post-mortem points. (For layout see Appendix G to Section 12, Part 3, Volume V). (3) A post-mortem point subroutine is placed at the beginning of each chapter of the programme, after the parameter table. 2.2 Post-Mortem Point Subroutine This subroutine is used for entry to and return from the post- mortem routine. Location Contents x ———> zero (link) x + 1 (set non~interruptible) x + 2 24.1.2 (to division O) x + 3 23.0.2 ———> (to post-mortem routine) x + 4 ———> zero x + 5 zero x + 6 26.0.1.x ———> (return to programme) Amendment No. 26 6/0 October 1964
Section 3 3 TRIALS SET-UP ROUTINE 3.1 Tasks (i) To set up trial data on input magnetic tape files. (ii) To replace instructions at post-mortem points by entries to the post—mortem point subroutines in the programme under trial. (iii) To list the instructions replaced, so that they may be obeyed before return to the programme. 3.2 Data (i) Details of specified post—mortem points and files of trial data held on the magnetic tape programme file (on route 7). (ii) Certain data obtained from Master Programme working locations in the store, concerning the whereabouts of the programme. (iii) The stored programme under trial. 3.3 Results The following results are produced by these routines: (i) Input magnetic tape files for the programme under trial. (ii) 'enter subroutine' instruction (26.0.0) replacing the instruction at each post—mortem point. (iii) A stored list of information for the post-mortem routines. 3.3.1 Magnetic Tape Files For each trial data file on the programme tape, a test is made on the set number to see if this file is to be written: (a) if the file heading was ignored by the Translator/08005, the set number has been specially marked and the file is not written. (b) if the set number is 9 the file is always written. (c) if the set number is equal to any one of the five digits in the 'trials' indicator on the allocation data (see Pt. 1, App. B.4) the file is written. The file is written on the indicated route with the requested file identity and run number. The file is terminated by the standard 'FINIS' block, and is rewound after having been written. The set number of the file is indicated by the rerun digit of the run number in the 'open file' comment as P.T.S. writes the data. Amendment No. 27 6/1 February 1965
Section 3.3 (Cont'd) 3.3.2 Entries to Post-Mortem Routines The instruction at each post-mortem point in the store at the time is replaced by an 'enter subroutine' instruction. The address of this instruction is the start of the post—mortem subroutine in the same chapter as the post-mortem point. Amendment No. 27 6/1 February 1965
Section 3.3 (Cont'd) 3.3.3 Stored Information The following information is stored in a list by the set-up routines: Location n Address of post-mortem point (in absolute form } unless post-mortem point is not yet in the store, } in which case in relative form) } } n + 1 Intercode serial number } } n + 2 Instruction replaced } } n + 3 Additional instruction * } } { N1 in binary (Q1 and Q2) (see para. 3.4.1) } { Allocation chapter number - i.e. chapter initially } n + 4 { occupying the store area later to be occupied by } { the chapter containing the post-mortem point (Q3), } { N2 in binary (Q4 and Q5) (see para. 3.4.1) } } { Number of chapter containing the post-mortem } First { point (Q1) } post- n + 5 { N5 (Q2 and Q3) } mortem { 24 action indicator (Q3) * } point { Type (Q5) } } n + 6 Section or chapter start (or parameter of a } transit area) } } n + 7 Section or chapter length } } n + 8 { Section number (Q1 and Q2) } { Transit area indicator (Q5) } } n + 9 { As for (n + 6), (n + 7) and (n + 8) for 2nd, } to { 3rd, and 4th sections } n + 17 { } n + 18 { As for n to (n + 17) for nine more post-mortem to { points n + 179 { * Note: The instruction which has been replaced is always stored in the list. If it is 24.0.0, 24.0,1, 24.0.3, or 24.1.2 instruction (modify next instruction) then the one which follows it is stored as the additional instruction and the 24 action indicator is set at 1. Otherwise the additional instruction stored is a instruction (set no indicators — i.e. an instruction with no effect) and the 24 action indicator is set at zero. Amendment No. 26 6/0 October 1964
Section 3.4 3.4 Organisation The set-up routine first obtains from a Master Programme parameter the start address of the programme's control area, from which certain programme details are obtained: start address of the special chapter, number of chapters, number of parameters, and modification group allocated. Next the programme's modification group is set, and the next block on the programme tape is read and tested for the presence of any of the following directives: 'FILES' this block contains information relating to a dumps point. 'CHAPT' heading block of a trial data file. 'E' indicates end of trials information. There is no directive in blocks that contain actual trial data. 3.4.1 Post-Mortem Points The information relating to each post-mortem point is stored in a 'list' consisting of 18 consecutive short compartments (see Section 3.3.3). The Intercode serial number of the post-mortem point, and the counters N1, N2 and N3, are stored for all dumps types. Then the type is tested and the appropriate details are stored, as follows: For a Chapter Dump: chapter number, start address, length. For a Section Dump: transit area parameter, length of section (where the section is a transit area). For a Section Dump: start and length of section. For a Location Dump: chapter number, relative address, reference and item, of the trace point. With each post-mortem point, a test is made to see if the specified procedure is in the store (which it will be, unless the ‘overlay’ facility is being used and the chapter concerned has not yet been loaded). If the post—mortem point is in the store, the instruction at that point will be stored in the list and replaced in the programme by a 26.0.0 instruction, which provides entry to the appropriate post-mortem point subroutine. In certain cases the next instruction will also be stored in the list (see note to Section 3.3.3). Allocated and actual chapter numbers will be the same, and both will be stored. Amendment No. 26 6/0 October 1964
Section 3.4 (Cont'd) If the post-mortem point is not in the store, i.e. the chapter in which it occurs is later to be read in, overlaying an existing chapter, only the actual chapter number will be stored at this stage. Other details will be dealt with as above by part of the post-mortem routine when the chapter concerned is loaded. 3.4.2 Trial Data The file on which trial data is to be written is specified in the heading block. The file is opened and the data from the programme tape copied onto the trial data file, using the programme's transit area. When the end sign 'FIEND' is reached after the last block of trial data, the file is rewound and the next block read from the programme tape. 3.4.3 End of Trials Information When the ‘E' block is reached the post-mortem routine is loaded into the store and entered. Amendment No. 26 6/0 October 1964
Section 4 4 OVERLAY AND POST-MORTEM ROUTINE 4.1 Tasks (i) To maintain a list of post-mortem points currently in the store. (ii) To set up post-mortem points when they are placed in the store, in a similar manner to the set-up routines. (iii) To decide, by referring to N1, N2, and N3 (see para, 3.1), whether the post-mortem is to be taken this time. (iv) If a post-mortem is to be taken, to ‘dump’ onto magnetic tape the contents of the specified part of the store, the registers A, B and C, and the modification registers. (v) To arrange that the instruction(s) replaced by the trials set—up routines are obeyed. 4.2 Data (i) The list of post—mortem point information stored by the trials set-up routines. (ii) Other working locations set up by the set—up routine. (iii) The special chapter of the programme under trial. 4.3 Results (i) A 26.0.0 instruction replacing the instruction at each post-mortem point in the overlaying chapter. (ii) An updated version of the list of post—mortem point information. (iii) 'Dumps' written at the end of the programme tape on route 7. Amendment No. 26 6/0 October 1964
Section 4.3 (Cont'd) 4.3.1 Layout of DUMPS Tape On entry from the P.T.S. set-up routine the following block is output: Word 0 } } Master Programme words 2 } 4 Master Programme Identity 6 Date 8 Time 10 Restart Mark Word 12 START 14 Programme Identity of Trial Programme 16 Address of End of Priority Queue 18 Block End Word At the beginning of each dump the following block is output; Word 0 } } Master Programme words 2 } 4 'DUMPS' 6 Type (1 char.), Heading block indicator (1 char.), section or chapter number (3 chars.) 8 Intercode serial number of post-mortem point, (Blank for initial dump or final dump) 10 } } } Contents of Register A } 12 } } (Blank for initial and } final dumps) 14 } } } Contents of Register B } 16 } } } 18 Contents of Register C } 20 } Contents of mod. register 1 } } of programme mod. group } 22 } } } 24 } Contents of mod. register 2 } (Blank for initial dump) } of programme mod. group } 26 } } } 28 } Contents of mod. register 3 } } of programme mod. group } 30 } 32 } M.R. setting for chapter or section length (types 1-5,10) } (most sig. short compt.) = 2 X no. of trace pts; (less 34 } sig.) = zero (type 6} 36 Block End Word Amendment No. 26 6/0 October 1964
Section 4.3 (Cont'd) At the beginning of each section or chapter (depending on the type of dump) the following block is output: Word 0 } } Master Programme words 2 } 4 'DUMPS' 6 Type (1 char.), Blank (1 char.), section or chapter number (3 chars.) 8 } . } . } Blank . } 30 } 32 } M.R, setting for chapter on section length (types 1-5,10) } (most sig. short compt.) = 2 x no, of trace pts; (less 34 } sign) = zero 36 } Block End Word Note: Types 1, 2, 3, 4, 5 and 6 are specified by the programe. Type 10 is the final dump. All subsequent blocks are of 27-word length and are as follows: Word 0 } } Master Programme words 2 } 4 } . } 24 5-character words holding information from 12 long . } words of store . } 50 } 52 Block End Word Amendment No. 26 6/0 October 1964
Section 4.4 In Type 6 dumps, the information for three trace points is held in a block in the following layout: Word 0 } } Master Programme words 2 } 4 Item of serial of Trace Point 1 } } 6 Q5 = tag; Q1-Q4 = reference of Trace Point 1 } } 8 Relative address of Trace Point 1 } } 10 15-bit address of Trace Point 1 } Trace } Point 12 } } 1 } Contents of the long word containing Trace Point 1 } 14 } } } 16 } } } Contents of next long word } 18 } } 20 Item of serial of Trace Point 2 . etc. . 52 Block End Word 4.4 Organisation The routines are entered from one of the post—mortem point sub- routines in the programme under trial, or from the Master Programme prior to unloading. On entry from the Master Programme after the programme is loaded, the special START block (see 4.3.1) is written and then the programme is entered. 4.4.1 Preparatory On entry to the post-mortem routines, the contents of registers A, B and C and of the programme's modification registers are stored, and the programme's modification group is set. If the entry is from the programme the value of N1 is tested: if it is non-zero, it is decreased by 1 and the end routine is entered; if it is zero, N3 is tested, and if this is also zero, the end routine is entered; other- wise N1 is replaced by N2, N3 is decreased by 1, and the dump is taken of the specified programme areas. Amendment No. 26 6/0 October 1964
Section 4.4 (Cont'd) 4.4.2 Overlaying The overlay routines are entered from the Master Programme overlay procedures. These routines distinguish between three types of post- mortem point: (i) Open: A post-mortem point which is currently in the store. (ii) Closed: A post-mortem point which has been overlayed by another chapter. In this case the absolute address of the post-mortem point will be held negatively. (iii) Not yet used: A post-mortem point which was not loaded initially by the Master Programme. In this case the set—up routines have stored information in relative address form. Each entry in the list is tested to see whether the dump is open, closed, or not yet used. 4.4.3 Post-Mortem Point Not Yet Used A test is made to see if this chapter has been loaded. If it has, the allocated chapter number in the list is set up as the chapter number of the chapter overlayed. The post-mortem point is set 'open' and the entry to the post-mortem point subroutine set up as in the trials set-up routines. The instruction(s) removed are stored in the list. 4.4.4 Post-Mortem Point Open The allocated chapter number is compared with the allocated chapter number of the overlayed chapter, and if they are equal the post-mortem point is closed by setting the absolute address of the post-mortem point negative. 4.4.5 Post—Mortem Point Closed The actual chapter number is compared with the chapter number of the overlaying chapter, and if they are equal the list value is opened by resetting the absolute address to its positive value. The over- layed chapter number is inserted as the allocated chapter number. The 26.0.0 instruction to the chapter heading subroutine is restored to the programme. 4.4.6 Programme Area Dumps (Initial Dump - Type 5, and Final Dump- Type 10) These are dealt with chapter by chapter, each chapter being preceded by a heading block. The start and end of each chapter are obtained from the special chapter of the programme. Amendment No. 26 6/0 October 1964
Section 4.4 (Cont'd) 4.4.7 Section or Chapter Dumps (Types 1 to 4) These are dealt with chapter by chapter or section by section, each one being preceded by a heading block. The start and end of each chapter or section are obtained from the list. 4.4.8 Location Dumps (Type 6) Each block of information contains details of three trace points. The heading block is followed by either one or two information blocks. 4.4.9 End Routines If entry was from the post-mortem point subroutine, the two instructions stored in the list are placed in locations (x+4) and (x+5) of the relevant post-mortem point subroutine (see Section 2). The link in the first location (x) of the subroutine is augmented by the 24 action indicator (see Section 3.3.3) so that the second instruction taken from the programme will not be obeyed twice. The contents of registers A, B and C and the programme's modification registers are re-stored and the programme is re-entered at location (x+4) of the post-mortem point subroutine. If entry was from the Master Programme at the end of a trial, tests are made to determine whether, on this installation, trials results are printed 'on-line'. If so, and a comparison post-mortem has been taken during the trial, the results routines are entered. Otherwise, the file is closed and the dumps must be printed off using the print-off programme (08002). Amendment No. 26 6/0 October 1964
Section 5 5 TRIALS RESULTS ROUTINE 5.1 Tasks (i) To perform a comparison if required. (ii) To print the results of the post-mortem. 5.2 Data The 'dump tape' output by the post-mortem routines. 5.3 Results A printout of the results of the post-mortem. The layout is given in Appendix A. 5.4 Organisation An end sign is placed on the dump tape and the tape rewound. The tape is then read in block by block. At the beginning of each section or chapter, the heading is printed. 5.4.1 Section and Programme Area Dumps These are tested to see if they are comparisons and action taken as follows: (i) If they are not comparisons they are stored and also printed. The initial dump is for later comparison only and is not printed. Only non-zero compartments are printed. (ii) If they are comparisons, they are tested against their values at the previous dump. Only if there is any difference are they printed. Both old and new values are printed in that order unless either is zero. The old value is indicated by an asterisk on the left-hand side. The information from the dump is then stored, ready for the next post-mortem. The final dump is printed as a post-mortem of the complete programme area. Amendment No. 26 6/0 October 1964
Section 6 6 TERMINATION OF P.T.S. Trial 6.1 Method of Termination There are three ways in which a trial can end: (i) The programme reaches end (obeys an Intercode 151 action). (ii) The operator abandons the programme by command. (iii) The operator abandons the programme by the 'abandon' option (option 1) to a Master Programme alarm (i.e. Alarm 1 - incurable doubtful block, Alarm 2 = incurable magnetic tape alignment failure, Alarm 3 - wrong magnetic tape reel number). Note: If the Master Programme alarm occurs during some Master Programme operation, e.g. programme or P.T.S. overlay, the effect of abandoning will be to prevent both P.T.S, and the programme from continuing; the dumps tape will not be complete, and the trial will have failed through no fault in the programme. This type of termination is therefore not discussed here. (i) Program End: Unless the 151 action was a dump point, no final dump is made. P.T.S. tests to see if the dumps that have been written are to be printed by P.T.S: this is done only if the installation's Master Programme parameter is set at 'print' and one of the dumps taken was type 2 or 4 (comparisons). P.T.S. will close the programme tape route at the end of the trial, and the final log comment will be END. If P.T.S. will not print the dumps, the programmer is to request programme 08002 to print them (see 08002 specification, Volume V, Part 2, Section 6 ). (ii) Abandon by Command: The effect of the command depends on what stage the trial has reached. If the set-up routine is still in the store, or if the trial has reached the stage of printing the dumps, the trial ends immediately with the log comment ABDON. If the post-mortem routine is in the store, P.T.S, will interpret the command as an instruction for it to take a final dump (after completing the current one, if the command interrupted this process) and then to print the results, if the conditions mentioned in 6.1 are satisfied. A log comment (see Section 7) is made while P.T.S. continues. If a second abandon command is now given the trial ends immediately. Amendment No. 27 6/1 February 1965
Section 6.2 Note that the abandon option produces a similar effect, and can be followed by an abandon command to terminate P.T.S. (iii) Abandon by Option: The effect again depends on which part of P.T.S. is in the store. If the set-up or print-off routines are in, the trial ends immediately with the log comment ABDON. When the post-mortem routine is in the store and is in control of the programme switch, the option is taken to refer to some P.T.S. file control order and the trial ends immediately; if the programme is in control of the programme switch, the effect is as for the abandon command, i.e. a final dump is made (and dumps printed if required) and the log comment 'OP ABANDONS' (see Section 7) is made. A second abandon by option now causes the trial to end immediately, as does an abandon command. 6.2 Off-Line Printing of Results The programme tape should be submitted to 08002 to print the dumps if this is not done by P.T.S. and the presence of dumps to be printed is indicated by: (i) the log comment END; or (ii) the log comment 'OP ABANDONS (programme)', where no abandon option was subsequently taken to a Master Programme alarm for this programme identity; or (iii) the log comment 'PTS ABANDONS (programme)', qualified as in (ii). In all other cases either the tape contains no dumps, or the tape is incomplete or unreadable. Amendment No. 27 6/1 February 1965
Section 7 7 LOG COMMENTS Where P.T.S. uses the programme switch, any peripheral error conditions (route closed, doubtful block, etc.) will be reported with the programme identity. When the Master Programme switch is being used by P.T.S, the programme identity in the comments will be 'O9001'. Apart from the 'open file' comments generated when setting up trial data files (which comments also give the programme identity), there are three comments originating within P.T.S. No comments are made for P.T.S. overlay. 'PTS ABANDONS (Programme identity)' This occurs when the post-mortem point subroutine has been entered from an address which is not in the post-mortem point list. This can happen when only the front end of a chapter has been overwritten by overlay, so that P.T.S. records show that the chapter is no longer in the store, but P.T.S. is being entered from the preserved part of the chapter. P.T.S. automatically takes a final dump, then prints it if appropriate (see section 6.1) and terminates the trial with an ABDON comment. 'OP ABANDONS (programme identity)' This is made to acknowledge the receipt of an 'abandon' command; P.T.S. will continue with a final dump (+ print if appropriate), and since any comments which might now be made will contain the programme identity, this comment is a reminder to the operator that P.T.S. not the programme, is using the programme switch (see also Section 6). 'TROFL (programme identity) (contents of A) (contents of B) (address or instruction)' This indicates that overflow has occurred in the programme at the indicated instruction, where registers A, B are displayed as at the end of the instruction. The programme continues. Amendment No. 27 6/1 February 1965
Appendix A APPENDIX A : LAYOUT OF STORE POST-MORTEM (P.T.S.) PRINTOUT OF DUMPS OF xxxxx TAKEN ON xx xx xx AT xx xx Printed at start of P.T.S. dumps printout MASTER PROGRAMME Printed before locations O-600 of a P.T.S. final dump xxxxx CHAPTER x Printed at the start of each chapter SECTION xx Printed at the start of each section PROGM xxxxx FINAL DUMP Printed at the start of the final dump FINIS Printed at the end PROGM xxxxx P.M. POINT xxxxx TYPE x } } Printed before each dump types A xxxxxxxxxx- B xxxxxxxxxx- C xxxxx } 1,2,3,4,6. } MR1 xxxxx xxxxx MR2 xxxxx xxxxx MR3 xxxxx xxxxx } Div. Div. Chapt. or Quartet Less Sig. Half More Sig. Half L.S.H. R.S.H. Alpha Tag No. Add. Sect. Add. Add. A d m Add. A d m Add. Quartets Quartets x xxxx xxxxx xxxxx xx x x xxxx xx x x xxxx xxxxx xxxxx xxxxx xx Printed for each long word Notes: 1 When printing dump type 6 (trace points) the division number is replaced by the reference of the trace point and the division 2 In the alpha word block end and line end characters are replaced by B and L respectively. Amendment No. 26 6/0 October 1964
Appendix B APPENDIX B : ANALYSIS OF TRIALS UNDER MASTER PROGRAMME This appendix is intended as a guide to the interpretation and analysis of post-mortems of trials under the Issue 6 Master Programme. It describes where information may be found which will be useful in analysing the course of a trial. Such information may be obtained from the comments in the log, from printouts of the store area, and from a knowledge of the contents of standard compartments in the store. File control blocks and print layouts are also dealt with. B.1 INFORMATION OBTAINABLE FROM LOG COMMENTS B.1.1 Log Entry for Allocation After the operator command to allocate and load a programme, an 'ALLOC' comment is typed in the log which records the facilities that have been allocated to the programme. The general layout of the allocation entry is on three lines: Line 1 : After the ALLOC comment are the programme identity; serial number; run and rerun numbers; allocated modifier group; trials, reverse or no alternate route allocation indicator (any combination of the letters T, N and R). Line 2 : Allocated chapter start points: these are given in chapter number order for the chapters to be loaded initially; the last entry in this line is the special chapter, which contains information associated with the programme for use by the Master Programme, also all annexes and conversion tables used by the programme. Line 3 : Route allocation: File identity, allocated route, allocated alternate route. ('N' in the allocated alternate route position indicates that no alternate route was allocated). The route number is given in channel and route form. An example of a log entry for allocation is given below: ALLOC 07135 00083 00010 M1 NR 1 0000 2 OOOQ 1 2332 B1 32 N A1 O6 N A2 05 N A6 04 N D1 42 N This indicates that reverse allocation without alternate routes has been made for programme 07135, serial 83, run number 1. It has been allocated modifier group 1 (i.e. registers using words 10', 12' and 14' of division O) It has two chapters initially, starting in division 1, location O and division 2, location O. The special chapter starts in division 1, location 2332. File B1 has been allocated channel 3 route 2 and no alternate route was allocated. File A1 has been allocated channel O route 6, etc. Amendment No. 27 6/1 February 1965
Appendix C APPENDIX C : LAYOUT OF PROGRAMME TAPE BEFORE AND AFTER A P.T.S. TRIAL BEFORE ___________________________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | ^ ^ ^ ^ P.L.S. all programme chapters | PTS set- PM points trial data | PTS PM routine | PTS print- | INDEX FINIS block | up routine (if any) sets (if any)| | off routine | details and end | | | | sentinels | | | | 'CHAP' 'E' 'CHIPT' 'PREND' block block block block AFTER As above up to P.T.S. print—off routine; then: __________________________________________________________________________________________________-----------------_______________ | | | || || || || || || | | | | | || || || || || || | | ^ ^ ----------------- PTS print-off | INDEX | main DUMPS subsidiary etc. main DUMPS subsidiary FINIS block routine | details | b1ock + first DUMPS block block + DUMPS block and end | | chap/section + second chap/ details + details sentinels | | detai1s section | | details | | | | <------first PM point obeyed---------><----second PM point obeyed---> <-final-> | | PM point | | (final) | | dump) 'PREND' 'START' block block Note that the final state of the programme tape is suitable for another P.T.S. trial, which will overwrite the previous START block + dump details with a new START block and the new dump details. Amendment No. 27 6/1 February 1965