COMTRAN Reconstruction

The language reference is this project’s reading of the two manuals, not IBM’s text. Every claim in it cites a page, and each citation opens that page beside its scan.

Part 7 of 10 of the COMTRAN Language Definition.

7. Special facilities and library conventions

This section covers everything in COMTRAN outside the Data and Procedure descriptions proper: the Environment Description (all seven card types, every field and default), the compiler control cards ($CMPLE, *FINISH) as source-visible language surface, the library system (COPY, LIBRARY, INCLUDE) as designed in 1960 and its deferral in 1962, program segmentation (OVERLAP/LOAD), renaming and linkage (CALL, ENTER, CONTRL), commentary (NOTE), and the CRYPT symbolic machine language facility. Throughout, J28-6169 (the 709/7090 processor manual) is authoritative for the implemented language; F28-8043 material is included where it defines features J defers or omits.

7.1 The Environment Description (J 02.06)

7.1.1 Purpose and position in the source program

The Environment Description "allows the programmer to specify the external physical factors which relate to the compilation and execution of the program … including physical characteristics of data, machine configurations, and programmer-elected features." These factors may usually be changed without affecting the logical description of the problem in the Procedure and Data Description parts (J 02.06.01.01).

A source program is divided into three divisions, each portion introduced by a division header, the division name preceded by an asterisk: *PROCEDURE, *DATA, *ENVIRONMENT. The divisions need not appear as separate entities; portions may be interleaved, but each portion must be labeled with its header, and all entries following a header belong to that division (F p. 27). (Division headers and overall program structure: see §2, Language structure.)

F/J divergence: F28-8043 reserves the environment division but does not define its content: it states only that each record must "also be named in the environment description, as specified in the publication covering the processor for each particular system" (F p. 71). The full card-level definition below exists only in J.

Appendix 90.08 of J describes the effect of Environment specifications on the Loader symbolic control cards generated by the Compiler (J 02.06.01.01); a summary is in §7.1.11 below.

7.1.2 Coding form, card layout, and continuation rules

The Environment Description coding form (Figure 1, J 02.06.01.02) has these fields:

Columns Field
1–3 CTL.
4–6 Serial
7–22 Name
25–30 Type
31–71 Description (options)
72 Continuation
73–80 Identification

Rules (J 02.06.01.01, J 02.06.02, J 02.03.01–02.03.03):

7.1.3 The seven card types

Seven type codes may appear in columns 25–30 (J 02.06.01.01): FILE, SPECIF, POOL, GROUP, CONTRL, OPTION, COND. Their general functions (J 02.06.02):

Card General function
FILE "must be included to describe the file characteristics which affect compilation, such as use for input or output and the type of blocking utilized."
SPECIF "describes such file characteristics as symbolic input/output unit assignments, density, relative activity, labeling conventions and other programmer choices which are to be punched during compilation into load-time control cards. SPECIF cards may be omitted if the programmer prefers to provide his own cards containing the appropriate information at load-time."
POOL "may be used by the programmer to direct the processor in the allocation of buffer storage for several files. In the absence of POOL cards, the processor will automatically make pool and buffer assignments."
GROUP "may be used by the programmer to specify buffer allocation for files belonging to a particular buffer POOL."
CONTRL "If several separately compiled programs are to be combined and executed as one program, any joint procedure or data description areas must be defined for the compiler by CONTRL environment cards."
OPTION "used when the programmer wants the processor to depart from its standard use of 709/7090 collating sequence, or when he wishes special emphasis placed on minimizing either storage or running time requirements in his object program."
COND "names and defines a computer console key setting which the programmer may want to test by procedure statements in his program."

7.1.4 FILE card

A FILE specification "must be made for each file processed by the program" (J 02.06.02). A maximum of 63 files may be described (J 90.01.04). No file check table is produced in the object deck (J 90.01.04).

General form, input files (J 02.06.03):

Name        Type    Description

file.name   FILE    INPUT    [ ,{BCD}    ]    [ ,{CARD} ]
                             [  {BINARY} ]    [  {TAPE} ]

                     ,BLOCKSIZE nn

                     [ ,ON ERROR statement.name.1 ]
                     [ ,FOR LABEL statement.name.2 ]
                     [ ,{HOLD}  ]    [ ,BEGIN ]
                        {SPANS}

                     ,record.name.1

                     [ ,{BLOCK CONTROL}               ]
                     [  {FIND LENGTH IN data.name.1}  ]
                     [ ,PLACE LENGTH IN data.name.2   ]

                     [ record.name.2 . . . ]

(The mark "nj" following record.name.1 on the source page is real typed characters, scan-resolved: not bleed-through, with the apparent trailing period a dust speck; it corresponds to no defined syntax element and is ignored. See §8.5.8.)

General form, output files (J 02.06.03):

Name        Type    Description

file.name   FILE    OUTPUT   [ ,{BCD}    ]    [ ,{CARD} ]
                             [  {BINARY} ]    [  {TAPE} ]

                     ,BLOCKSIZE nn

                     [ ,FOR LABEL statement.name.2 ]

                     [ ,BEGIN ]    [ ,SPANS ]

                     ,record.name.1

                     [ ,FIND LENGTH IN data.name.1  ]
                     [ ,PLACE LENGTH IN data.name.2 ]
                     [ ,PRIMARY ]    [ ,NO CONTROL WORD ]

                     [ ,record.name.2 . . . ]

General form, checkpoint files (J 02.06.04):

Name        Type    Description

file.name   FILE    CHECKPOINT

Option ordering rule: "The order in which options are exercised on the FILE card is critical only in that the options exercised for a particular record must be listed following the record.name and prior to the introduction of another record.name" (J 02.06.04).

Option-by-option (J 02.06.04 – 02.06.07):

The standard variable-length record control word (one word, IOCTN 0,,length.of.record.in.words. for binary, six BCD characters of length for BCD records) precedes each standard variable-length record on tape and in the buffer, is not describable or addressable by the programmer, but must be counted in BLOCKSIZE (J 02.07.03; see the Input/output section).

Further field-test restrictions folded in from J 90.01.01: all input records containing arrays are processed in the transmit mode; records from different files REDEF'd together are not automatically transmitted (SPANS or HOLD must be used).

Checkpoint files: designating a FILE CHECKPOINT (with SPECIF CHECKC/CHECKF on data files, §7.1.5) is the language surface of the checkpoint facility. IOCS module choice follows: "Normally the MINIMUM module of IOCS is used with the object program. If checkpoints are desired or specified BASIC IOCS is used. If labeling exists the LABELS version of IOCS is necessary" (J 90.01.05). Restart is an operator procedure (J 05.04), not a language feature.

The PATTERN puzzle: the GET verb discussion allows GET RECORD FROM file.name when "All records in the file which will be obtained by this form of the command are included in a PATTERN in the Environment Description" (J 02.07.04), and three compiler diagnostics govern it: "NO RECORDS SPECIFIED IN -PATTERN- ON -FILE- CARD FOR 'NAME.1'.", "SINGLE RECORD IN THE -PATTERN- ON -FILE- CARD … INEFFICIENT PROGRAM PRODUCED", and "NUMBER OF RECORDS IN -PATTERN- CANNOT EXCEED 16" (errors 48,00–50,00, J 90.04); yet no PATTERN option appears in the FILE card general forms (J 02.06.03). See ambiguities.

7.1.5 SPECIF card

"The SPECIF card is used to describe load time I/O options for the designated file. SPECIF cards are not necessary for correct compilation … the user may elect to punch the required load time cards himself. … The SPECIF card(s) may appear anywhere within the environment division" (J 02.06.07).

General form (J 02.06.07):

Name    Type      Description

        SPECIF    file.name  [ ,UNIT1 'unit.1' ]  [ ,UNIT2 'unit.2' ]

                  [ ,{LOW}  ]   [ ,DEFER ]   [ ,OPENW ]   [ ,OPENF ]
                     {HIGH}

                  [ ,{CLOSER} ]   [ ,ACTIVITY nn ]   [ ,{CHECKC} ]   [ ,MULTI ]
                     {CLOSEW}                            {CHECKF}

                  [ ,SEQ ]   [ ,CKSUMS ]

                  [ ,{LABELS} ]   [ ,SERIAL 'ser.no' ]   [ ,REEL 'reel.no' ]
                     {LABELN}

                                [ ,RETAIN days ]   [ ,{HIGH} ]
                                                       {LOW}

UNIT1 'unit.1' / UNIT2 'unit.2': "Note that the Quote Marks are mandatory." The alphameric literals specify symbolically the I/O units (card or tape) to which the file is attached: relative unit assignment, symbolic channels, and tape transport model type. UNIT2 assigns the secondary reel of a multi-reel file, automatically referenced upon a reel switch; "If UNIT2 is left blank, the secondary unit assignment will be the same as the primary unit" (J 02.06.08). Notation (J 02.06.08):

Symbol Meaning
X one of the real channels A,B,…,H
P a symbolic (unspecified physical) channel S,T,…,Z
k one of the numbers 1,…,9,0
m a tape transport model number, II or IV

Allowable unit specifications (J 02.06.08–02.06.09):

Form Meaning
(none) any available unit is assigned
'm' any available unit of this model type
'X' any available unit on this physical channel
'P' all files in the job with this symbolic channel designation are assigned to the same channel
'X(k)' the kth available unit on the specified channel; "the parenthesis are required"
'Pm' any available unit of this model type on the symbolic channel
'Pkm' an available unit on the symbolic channel, having this model number; k without parenthesis is the order of preference for the channel (lower numbers assigned to the same channel first when units are scarce)
'IN' the current system Input unit contains the file
'OU' the current system Output unit, for a printed output file
'PP' the current system Peripheral Punch unit, for a punch output file
'UTk' System utility tape k (non-parenthesized k = 1–4)
'RDX' card reader, channel X
'PRX' printer, channel X
'PUX' card punch, channel X
* in UNIT2 secondary unit is any unit on the same channel and of the same model type available after all other assignments; at load time a different-model unit may be substituted, or no secondary unit assigned if none available (J 02.06.09)

Examples: first available unit on channel A: , UNIT1 'A(1)'; system output tape: , UNIT1 'OU'. "Note, that in this case (also for 'IN') included options for density, opening and closing are non-effective" (J 02.06.10). Further unit-assignment information is in Loader section 03 (J 02.06.10).

Restrictions (J 90.01.04): "Absolute tape assignment cannot be made; symbolic and relative assignment techniques are used." "Unless system utility tapes (UTk) are explicitly designated the drives assigned to them are not used at execution time as object program units."

Remaining options (J 02.06.10 – 02.06.12):

Option Meaning Default if absent
LOW / HIGH (first occurrence) density of the tape HIGH (J 02.06.10)
DEFER file not required when processing begins file must be mounted before program processing commences (J 02.06.10)
OPENW do not rewind before opening file rewound prior to being opened (J 02.06.10)
OPENF this standard labeled file is found on a multi-file reel by searching forward on labels; without OPENW the tape is rewound before searching. With OPENW+OPENF the programmer must insure (1) the tape is positioned before a header label and (2) the labeled file sought is further down the tape (J 02.06.10) no forward search
CLOSER / CLOSEW CLOSER: file only rewound upon closing; CLOSEW: file not rewound upon closing (J 02.06.10) rewind and unload on close (J 02.04.06; J 90.08.02 codes this default "U")
ACTIVITY nn nn = 1–99, relative activity (usage) of this file, used by the loading-time program in allocating buffer areas (J 02.06.11) —
CHECKC / CHECKF CHECKC: checkpoint written on the checkpoint file upon reel switch of this file. CHECKF: checkpoint written on this file upon reel switch; "the file must be a labeled output file for this option to be operative" (J 02.06.11) "No check point will be written if neither option is exercised"
MULTI tape file contained in more than one reel "A single reel file is assumed" (J 02.06.11)
SEQ each block contains a block sequence number to be checked by the I/O system (J 02.06.11) no sequence check (J 02.07.06)
CKSUMS each block carries a checksum of data to be checked by the I/O system (J 02.06.11) no checksum check (J 02.07.06)
LABELS / LABELN LABELS: standard label, "checked or written automatically by IOCS." LABELN: non-standard label, "a label of 14 words or less which is to be checked by the programmer using a linkage supplied by the FOR LABEL option of the Environment FILE card." "Either LABELS or LABELN must be explicitly stated if labels are to be recognized by IOCS" (J 02.06.11) "the file is considered to be unlabeled"
SERIAL 'ser.no' alphameric literal of 5 or less characters. Standard input labels checked against it if non-blank; standard output labels contain it only if REEL specifies a 'reel.no' greater than 1: "output serial numbers are normally taken from the label already present on the tape on which the first reel of the file is written" (J 02.06.12; "lables" sic) —
REEL 'reel.no' alphameric literal of 4 or less numeric characters: reel sequence number of the first reel; "adjusted at object time to reflect reel switching, and is checked in standard input labels" (J 02.06.12) assumed to be 1
RETAIN days numeric literal of 3 or less numeric characters: days the tape is retained from the date written. Writing a labeled file on the tape before expiry produces an on-line IOCS error. "Unless a labeled file is to be written on a tape, the system assumes that no label is present on the tape" (J 02.06.12) —
HIGH / LOW (after LABELS/LABELN) density of the label. "Label dinsity is assumed to be that of the file if no specification is made" (J 02.06.12; "dinsity" sic) file density

SERIAL, REEL and RETAIN may be given for standard or non-standard labels; the information is kept in the IOCS file block, printed on-line in certain error situations, used by IOCS for standard labels only, and available to the programmer for non-standard label handling (J 02.06.12).

7.1.6 POOL card

The POOL card lets certain files share a common buffer area; optional. "If POOL specifications are not provided at all, files will be grouped automatically by IOCS," and the information may alternatively be entered on an object-time loading card (J 02.06.13).

General form (J 02.06.13):

Name        Type    Description

pool.name   POOL    file.name.1   [file.name.2.....]

                    [, BUFFERCOUNT nn]

                    [, BLOCKSIZE nn]

7.1.7 GROUP card

Used in conjunction with a POOL card to specify how buffers within a POOL are shared; optional. "If GROUP specifications are not made at all, the compiler will attempt to assign at least 2 buffers to each file" (J 02.06.13–02.06.14).

General form (J 02.06.14):

Name    Type     Description

        GROUP    [pool.name]

                 [, OPENCOUNT nn]

                 [, BUFFERCOUNT nn]

                 , file.name.1   [, file.name.2.....]

7.1.8 CONTRL card — inter-program areas (deferred)

"The CONTRL cards define procedure and/or data areas common to two or more Commercial Translator programs. These programs may be compiled and checked out independently and then merged at object loading time into one running program" (J 02.06.15).

General form (J 02.06.15):

Name     Type      Description

loadnm   CONTRL    { section.name
                     sentence.name.1   TO   sentence.name.2
                     record.name }

Restrictions (J 02.06.15–02.06.16):

Deferral (J 90.01.04): "Mechanization of multiple deck combination has been deferred. CONTRL specifications will have no effect on the object deck produced by the Compiler, i.e., no control break table is punched." Correspondingly, "The control break table is not processed by the loader. This implies that multiple program loading with cross references by means of control breaks is not available" (J 90.01.05). (The object-deck layout still reserves a Control Break Table position, J 02.02; see the object-deck section.) The compiler nonetheless diagnoses CONTRL card format errors (176,00, J 90.04).

7.1.9 OPTION card — collating sequence and space/time conservation

"OPTION cards may be used to set compilation mode switches within the compiler" (J 02.06.16). The compiler normally generates comparison instructions based on the 709/7090 collating sequence and an object program "conservative of time rather than space"; the OPTION card selects the Commercial (705) collating sequence and/or a time- or space-conservative object program (J 02.06.16).

General form (J 02.06.16):

Name   Type     Description

       OPTION   [COLLATE COM]                 [IN section.name]

                [, CONSERVE {SPACE}]           [IN section.name]
                            {TIME }

The two collating sequences, lowest to highest (J 02.06.16; scan-resolved reading — glyph legend and details in §1.1):

709/7090:    0 through 9   =   '   +   A through I   ⟨+0⟩   .   )   −   J through R   ⟨−0⟩   $   *   blank   /   S through Z   ⟨rm⟩   ,   (

Commercial (705):  Blank   .   ⟨loz⟩   ⟨gm⟩   &   $   *   −   /   ,   %   #   @   ⟨+0⟩   A through I   ⟨−0⟩   J through R   ⟨rm⟩   S through Z   0 through 9

COLLATE COM also changes the figurative constants: HIGH.VALUE is ( and LOW.VALUE is 0 under the 709/7090 sequence; under COM, HIGH.VALUE is 9 and LOW.VALUE is blank (J 02.04.01; see §2/§4 on figurative constants).

7.1.10 COND card — console entry keys

"The COND card defines a computer console entry keys setting which may be interrogated by procedure statements" (J 02.06.17).

General form (J 02.06.17):

Name             Type    Description

condition.name   COND    KEYS 'nn'

"The alphameric literal 'nn' is composed of 12 octal digits representing 'on' settings of the 36 console entry keys. When the condition.name is tested in a procedure statement only the keys specified in 'nn' are tested for 'on' setting. The specified console keys must all be 'on' for the condition to be true. No 'off' or 'on' test is made for the non-specified keys. Note that Data Description condition.names are tested differently, i.e., for absolute equivalence to the specified value" (J 02.06.17).

Compiler behavior on malformed COND cards (J 90.04): key setting exceeding 12 digits: rightmost 12 digits used (error 6,00); non-octal key setting: key setting '1' used (error 7,00); format error: 4,00; missing name in columns 7–22: 88,00.

Do not confuse this Environment COND card with the Data Description type code COND (condition values of a conditional variable; see §3).

7.1.11 Environment cards → Loader symbolic control cards (J 90.08)

The Compiler turns Environment FILE/SPECIF information into Loader *FILE and *SPEC symbolic control cards (J 90.08.01–90.08.02). Key mappings a compiler writer needs (full field tables at J 90.08.01/90.08.02):

CLOSE ALL FILES closes each open file according to these *SPEC close options; "In the absence of specification, closing includes a rewind and unload of the unit. Files closed by this form of the CLOSE command may not be subsequently reopened by the program" (J 02.04.06 — note that page cites the SPECIF card as "Section 02.07"; it is actually defined at J 02.06.07). STOP RUN closes all open files as if CLOSE ALL FILES had been supplied (J 02.04.06).

7.2 Compiler control cards ($CMPLE, *FINISH) (J 02.01)

These cards are part of every source deck and are the compiler's source-visible control surface. They exist only in J; F has no counterpart.

7.2.1 $CMPLE card

"A $CMPLE card must precede each source language program. It is recognized by the Commercial Translator Monitor (CTM) for purposes of operational control and interpreted by the … compiler to initiate processing of source language statements" (J 02.01.01).

General form (J 02.01.01):

1  -  6      8  -  13       16
$CMPLE       deck.name      [NODECK]        [,LIST]         [,DICT]
                            [,LOAD]         [,LOGIC]        [,FILES]
                            [,MAP]          [,NOGO]

             55        -        72
             [secondary.identifier]

7.2.2 *FINISH card

"The *FINISH card delimits the extent of the source language statements to be compiled" (J 02.01.02):

7
*FINISH

"Note that this card must be followed by an end of file (see 04.02 and 05.03)" (J 02.01.02). In the stacked-job deck, "This card precedes end-of-file on COMPILE jobs" (J 05.03).

Related deck-level facts a compiler writer should know (J 02.02, J 02.03.01): normal output is a relocatable column-binary deck (symbolic control cards, *CTEXT, relative binary program deck with Control Break Table / File Check Table / Text, *CTEND; see the object-deck section, J 90.03); the listing assigns statement numbers of the form xxxxx,00 (clause number after the comma; 9999,99 references errors not confined to a single statement); and "Card serial numbers in columns 1-6 of source decks are not sequence checked by the compiler" (J 02.03.01). F/J divergence: F states serial numbers "will be sequence-checked by the processor" (F p. 37).

7.3 The library system — COPY, LIBRARY, INCLUDE (F design; deferred in J)

7.3.1 The library concept (F)

F envisions a program library holding both procedure and data descriptions. On the procedure side: "If such a routine has been stored in a 'library,' the programmer may be able to call for it by using the verb INCLUDE … This verb, therefore, may be used in building the object program, but it will not be used as a part of the object program itself" (F p. 12). On the data side: "the data description can actually be stored in the library, on tape or in cards, so that it can be called for when needed" (F p. 62). No physical library format or maintenance utility is defined in either manual.

J status: "Mechanization of the INCLUDE verb has been deferred, and consequently no library facilities are currently available" (J 90.01.02). "Implementation of COPY has been deferred" (J 90.01.03). The compiler diagnoses: "-COPY- AND -LIBRARY- ARE NOT YET HANDLED BY SYSTEM." (error 110,00, J 90.04 — the listing's CODE column prints 0 only as a placeholder; the actual severity 1–5 printed with the message is unspecified); so the 1962 compiler recognizes these constructs and diagnoses them, rather than treating them as undefined. INCLUDE and LIBRARY remain reserved (they may not be used as Data or Procedure names, J 02.03.02).

7.3.2 The INCLUDE command (F only)

"The INCLUDE command causes the processor to extract a unit of procedure from the library and to insert it in the present program" (F p. 58). Basic forms (F p. 58):

INCLUDE library.procedure
INCLUDE HERE library.procedure

. . . WITH new.name.1 FOR old.name.1, new.name.2 FOR
     old.name.2, ... new.name.n FOR old.name.n

replaces all occurrences of the old.names with the new.names, "done by the processor at the time the procedure is included" (F p. 58). Full consolidated general form (F p. 109):

INCLUDE [HERE] library.procedure [AS procedure.name] [WITH new.name.1 FOR
    old.name.1, new.name.2 FOR old.name.2, ... new.name.n FOR old.name.n]

7.3.3 The COPY type code (F pp. 76–77; deferred in J)

"This type code is used to copy a data description previously defined in the program so that it can be used again elsewhere," with a new name and, if desired, new level numbers (F p. 76). Usage: the new name goes in the Data Name columns, COPY in the Type columns, and the original name in the Description columns. "This description must already have been read into the system for the COPY code to be able to operate on it" (F p. 76).

The processor copies the original description in its entirety except: (1) the original name is replaced by the new name; (2) if a new level number is specified, all subordinate level numbers are adjusted to retain their original relationship: e.g. an original sequence 01, 03, 04 copied at level 05 becomes 05, 07, 08 (F p. 76). Worked example (F pp. 76–77): PAY.RCD.DETAIL 02 COPY … PAY.RCD.MASTER expands the whole PAY.RCD.MASTER hierarchy under the new name with levels 02/03/04.

7.3.4 Library names in the Description columns (F only)

The Description columns (38–71) of a data description entry may contain, among other things, "Data names associated with the type codes REDEF and COPY" and "The word LIBRARY, followed by the name of a data description stored in the library"; when several kinds of information appear on one line they must be written in the prescribed order, separated by one or more blanks (F p. 79). "The word LIBRARY, followed by the name of a data description stored in the library, designates a data description which is to be copied. … When a library data description is prescribed, the type code COPY must be used" (F p. 81).

In F's reserved-word list, COND, COPY, FUNCT, LABEL, LIBRARY, PARAM, QUANTITY and REDEF are daggered: "These words have a restricted usage only in data description; they may be used freely in procedure description" (F p. 110). In J, LIBRARY (but not COPY) appears in the key-word list of words that "may not be used as Data or Procedure names" (J 02.03.02); type codes are recognized positionally in the Type columns.

7.4 Program segmentation — OVERLAP and LOAD (F design; deferred in J)

J status: "Implementation of these verbs [LOAD and OVERLAP] has been deferred" (J 90.01.03); "Deferred implementation of the LOAD-OVERLAP verbs implies that programs may not be segmented into separate memory loads at this time" (J 90.01.05). Both remain reserved words in J (J 02.03.02). The following is the F design.

7.4.1 OVERLAP (processor command)

"An object program … is organized as one loading of storage unless the programmer specifies otherwise by means of the OVERLAP command. This command designates portions of the program that are to occupy (at different times) the same area in internal storage" (F p. 55). General form (F p. 55):

OVERLAP procedure.name.1, procedure.name.2, ...
     procedure.name.n

Rules and object-program organization (F pp. 55–56):

7.4.2 LOAD (program command)

General form (F p. 54):

LOAD procedure.name

"procedure.name" is a portion of the program which, at object time, will be waiting in external storage; LOAD brings it into the area shared by the procedures of the associated OVERLAP command, replacing (retrievably) the previous occupant. "Any unit of procedure addressed by a LOAD command must be named in an OVERLAP command" (F p. 54).

Note the F/J structural distinction: LOAD is a program verb (miscellaneous category, with DISPLAY), OVERLAP a processor verb (F p. 35).

7.5 Renaming and linkage — CALL, ENTER, CONTRL

7.5.1 CALL (processor command)

"The CALL command is used to specify alternate names, or synonyms, for previously defined names" (F p. 59). General form (F p. 59):

CALL (old.name.1) new.name.1, (old.name.2) new.name.2, ...
     (old.name.n) new.name.n

J amplifications and restrictions:

7.5.2 ENTER — entering another language

F design: "The ENTER command instructs the processor to accept statements in another language" (F p. 59):

ENTER coding.language

"To revert to the Commercial Translator language, another ENTER command is required, specifically: ENTER COMMERCIAL TRANSLATOR." Details of the particular symbolic languages were left to the processor publications (F p. 59).

F/J divergence (implemented forms): "There are only two forms which this command may take: ENTER CRYPT and ENTER COMMERCIAL TRANSLATOR. The first form signals the processor that the following instructions are to be processed by CRYPT, the SCAT-like machine symbolic assembler of Commercial Translator. The second form … terminates the processing of CRYPT instructions and signals that Commercial Translator statements follow" (J 02.04.02.01). No other coding language can be entered in the 709/7090 implementation; there is no other inter-language linkage facility at the language level. (System subroutines such as IOCS are linked automatically by the Loader; cf. the LOGIC option, J 02.01.02.)

The returning form is punched with ENTER as an operation code and COMMERCIAL TRANSLATOR as a variable-field entry beginning in column 16 of the SHARE coding form (J 02.08.03).

7.5.3 Inter-program linkage

Language-level linkage between separately compiled COMTRAN programs is the CONTRL card mechanism (§7.1.8) (common procedure/data areas equated at load time via a 6-character loadnm) and it is deferred in J (J 90.01.04). Parameter passing at the language level exists only within a program, via DO … USING/GIVING and BEGIN SECTION USING … GIVING (F pp. 57–58; see §4, Procedure description). The associated Data Description type codes PARAM and FUNCT "are no longer in the language" in J (J 02.05.03), a further F/J divergence.

7.6 Commentary conventions — NOTE and the period-blank rule

"The NOTE command enables the programmer to place explanatory information in the listing of the program" (F p. 59). General form (F p. 59):

NOTE any sentence.

Additional commentary channel in J: "Procedure statements are terminated by the first period (.) followed by a blank. Any information following this period blank is considered to be commentary" (J 02.03.01); a period-blank "terminates analysis of the statement except when they appear within an alphabetic literal; any information in the same card which follows the period is assumed to be commentary. No diagnostic comment is made" (J 90.01.03). The period-blank terminator is not used in the Data and Environment divisions (J 02.03.02; J 02.06.02).

7.7 The CRYPT facility — 709/7090 machine symbolic language (J 02.08)

CRYPT exists only in J; F merely promises access to "the symbolic 'one-for-one' language of the particular machine system" via ENTER (F p. 59).

7.7.1 What it is and where it may appear

"The 709/7090 Commercial Translator System provides the programmer with the ability to include symbolic machine language instructions and data description at any logical point in his program. The procedure command, 'ENTER CRYPT' signals the System that the ensuing source statements are in symbolic machine language form. The object instructions generated from these statements will be located immediately following the last word generated from the preceding Commercial Translator statement. The symbolic machine language acceptable to the system is similar to SCAT, with several restrictions and some additional flexibility. The standard SHARE 709/7090 coding form is used for CRYPT statements" (J 02.08.01). Compilation of CRYPT is part of the compiler's normal input alongside the three divisions (J 02.00.00). Processing of CRYPT instructions is terminated by ENTER COMMERCIAL TRANSLATOR (J 02.08.03; §7.5.2).

7.7.2 CRYPT rules (restrictions relative to SCAT) (J 02.08.01–02.08.02)

  1. The Commercial Translator special characters cannot be used as part of symbols; "The same rules which are applied to Commercial Translator names are applied to CRYPT names." Examples of illegal or specialized usage: L(5) is interpreted as the fifth element of array L; .AB.: a period may not be the first or last character of a symbol; A'B)$: quotation mark, left parenthesis, right parenthesis and dollar sign may not be part of a symbol (J 02.08.01).
  2. "No SCAT macros are acceptable" (J 02.08.01).
  3. Pseudo-ops usable: OCT, PZE, etc. (both MZE and FOR sets), EQU, BSS, BES, BCI (J 02.08.01).
  4. Pseudo-ops not usable: HEAD, VFD, DEC, DUP, ORG, SYN, END (J 02.08.02).
  5. "Literals are not presently permitted in machine language" (J 02.08.02).
  6. Qualified names may not be referenced by CRYPT instructions (CLA MASTER NAME is incorrect); CALL may be used to reduce a qualified name to a single unique name (J 90.01.01; J 02.03.03).

7.7.3 Flexibility above SCAT (J 02.08.02)

  1. Names defined in the Commercial Translator sections may be referenced in the variable field, so variable-field names may contain up to 30 characters (compound names excepted; rename via CALL outside the CRYPT section).
  2. Array elements are addressed through "Symbolic Registers": CLA A(I,J) is replaced by CLA* SRAIJ, where the Symbolic Register always contains the address of the element for the present values of I and J. "The system will not check for changes in component variables while in the machine language mode"; the Symbolic Register is not updated if the programmer changes I or J in CRYPT. "Also, indirect addressing is not permitted on the original operation."
  3. Arithmetic expressions in the variable field may contain parentheses, e.g. AXT A*(B + C),4.
  4. The Commercial Translator Data Description form serves for describing data and entering constants (no DEC/VFD needed).

7.7.4 Generated-code caveats (J 02.08.03)

References to fields of records processed in locate mode do not expand one-for-one. For CLA DATE where DATE is a field of a located record, the system generates:

LAC     BASE.LOCATOR.OF.DATE,4
TXL     SYS)294,4,0
CLA     DATE.DISP,4

where BASE.LOCATOR.OF.DATE holds the current origin of the record, SYS)294 is an error routine reporting an unset base locator, and DATE.DISP is the field's displacement within the record. "Note that the contents of index register 4 are destroyed, and that instructions have been inserted in the program. Care must be taken to avoid incorrect referencing when relative addressing using * to signify the location counter is used" (J 02.08.03). (Generated-code details: see the generated-code section, J 90.02.)

7.8 F/J divergence summary for this section

Feature F28-8043 (June 1960) J28-6169 (Jan 1962), authoritative
Environment Description content Division reserved (*ENVIRONMENT, F p. 27) but undefined; deferred to processor manuals (F p. 71) Fully defined: FILE, SPECIF, POOL, GROUP, CONTRL, OPTION, COND cards (J 02.06)
Library facilities INCLUDE, COPY, LIBRARY defined (F pp. 58, 76, 81) All deferred; "no library facilities are currently available" (J 90.01.02–03; error 110,00, J 90.04)
LOAD / OVERLAP segmentation Defined (F pp. 54–56) Deferred; no segmented memory loads (J 90.01.03, 90.01.05)
Multi-program combination (CONTRL) Not in F Defined (J 02.06.15) but mechanization deferred; no control break table punched or processed (J 90.01.04–05)
ENTER ENTER coding.language, open-ended (F p. 59) Exactly two forms: ENTER CRYPT, ENTER COMMERCIAL TRANSLATOR (J 02.04.02.01)
CRYPT Not defined (implied by ENTER) Fully defined SCAT-like assembler (J 02.08)
PARAM / FUNCT type codes Defined (F pp. 73) "no longer in the language" (J 02.05.03)
CALL Synonyms for previously defined names (F p. 59) Same, plus: old.name unique, no subscripts, avoid record.names (J 02.04.05, 90.01.01)
NOTE Defined (F p. 59) Unchanged in substance; period-blank commentary rule amplified (J 02.03.01, 90.01.03)
Serial-number sequence checking "will be sequence-checked by the processor" (F p. 37) "not sequence checked by the compiler" (J 02.03.01)
Compiler control cards Not in F $CMPLE, *FINISH (J 02.01)
Checkpoint facility Not in F FILE CHECKPOINT + SPECIF CHECKC/CHECKF (J 02.06.04, 02.06.11)