IBM 1620 User Manual

Error Analysis Phase
Restart Procedure
Final Program Summary
After an error has been deteced in a statement, and the appropriate error code
has been typed, the original error statement is typed. If switch 3 is off, the car-
riage is returned and the program halts to wait for a corrected statement to be
typed in. After reviewing the erroneous statement and the error code or codes
indicated,
you can, in most cases, make an immediate correction to the statement.
Type the correct statement (followed by a record mark), then press the release
and.
start keys. The program resumes by analyzing the statement just typed to
determine if any errors still exist. If the statement is correct, the program will
begin analyzing the next statement in the FORTRAN program.
In some cases, it may not be possible to re-enter a corrected statement with-
out certain modifications because part of the statement has already been proc-
essed as a correct statement.
For example, if an error is discovered in a transfer
statement (GO TO), you must enter the correct statement with a statement num-
ber to avoid error STNO 4, or enter it twice without a statement number. (The
program considers the first part of the GO TO to be correct, and requires that any
statement following a transfer statement must contain a statement number).
When a statement containing a statement number is partially processed due
to an error, you cannot re-enter the statement with the statement number be-
cause an error
STNO 2 will result.
In an erroneous DIMENSION statement, for example DIMENSION C ( N ), the C
is stored as a nonsubscripted variable and cannot be used later in the program
as a subscripted variable. In case of C( 10,N), the C is stored as a one-di-
mensioned variable.
Restart of the Pre-Compiler is necessary.
For expressions involving involution (raising to a power), the exponent
cannot have an involution operation. For example, A * * (B * * 2. +.1) will result
in erroneous operation of the Pre-Compiler. This restriction also applies to the
arithmetic expression in an IF statement.
There is no check for the termination of a DO loop. If a dimension specifica-
tion exceeds
the capacity of the storage, erroneous results will follow.
If an immediate correction cannot be made, you can resume testing of the
next statement by manually branching to BEGIN (see RESTART PROCEDURES).
It is important to note that if a new source program is being punched, by-
passing
the error correction routine will result in the incorrect statement being
punched into the output tape or cards.
The normal operation of the Pre-Compiler program is to type incorrect
statements only.
If you require a typed copy of all statements, turn on program
switch 1.
You may find it necessary during processing to interrupt the normal operation
of
the program. To allow such interruptions, the following re-entry points, given
by symbolic label and storage location, are available:
CLEAR location 01208: The symbol table and table of statement numbers
referenced by DO statements are cleared. CLEAR is the restart point for a
new program to be tested.
INITL location 01340: The table of statement numbers referenced by
DO statements is cleared.
BEGIN location 01472: No tables are cleared, but the program will con-
tinue to
read source program statements. BEGIN is the normal entry
point for restarting after a check stop or other interruptions of the
Pre-Compiler.
After the END statement in a source program has been processed by the Pre-
Compiler program, a final program summary is typed on the console typewriter.
The FORTRAN Pre-Compiler Program 75

IBM 1620 Specifications

General

Category	Desktop
Manufacturer	IBM
Model	1620
Introduced	1959
Weight	Approximately 1, 000 pounds
Memory	20, 000 to 60, 000 digits
Programming	FORTRAN, Symbolic Programming System (SPS)
CPU	Decimal, variable word length
Storage	Magnetic disk drive (IBM 1311)

Summary

Introduction to IBM FORTRAN

Writing the 1620 FORTRAN Program

Floating Point Arithmetic Explained

Details floating point arithmetic, mantissa, and exponent representation.

FORTRAN Constants: Definition and Types

Defines constants and explains fixed and floating point constant formats.

FORTRAN Variables: Definition and Naming

Explains variables, their distinction from constants, and naming conventions.

FORTRAN Subscripts and Arrays

Explains subscripts for referencing array elements and defining arrays.

Arithmetic Statements

Describes how numerical calculations are defined using arithmetic statements.

FORTRAN Expressions: Structure and Operations

Defines expressions and lists the basic FORTRAN operation symbols.

Control Statements

Explains control statements that provide flexibility in program development.

Unconditional GO TO Statement

Describes the unconditional GO TO statement for transferring program execution.

Computed GO TO Statement

Explains the computed GO TO statement for conditional transfers.

IF Statement for Conditional Logic

Details the IF statement for transferring program flow based on expression values.

DO Statement for Looping Constructs

Explains the DO statement for simplifying loop programming and providing flexibility.

Nested DO Statements and Rules

Explains the rules for nesting DO statements within other DO statements.

Input/Output Statements

Explains statements used to read data into programs and output results.

READ Statement for Card Input

Details the READ statement for inputting data from punched cards.

ACCEPT Statement for Typewriter Input

ACCEPT TAPE Statement for Paper Tape Input

PUNCH Statement for Card Output

TYPE Statement for Typewriter Output

PRINT Statement for Printer Output

Explains the PRINT statement for outputting data to the 1443 Printer.

PUNCH TAPE Statement for Paper Tape Output

FORTRAN Specification Statements

Introduces specification statements, including FORMAT and DIMENSION.

FORMAT Statement for Data Conversion

Explains the FORMAT statement for controlling input/output data conversion.

FORMAT Statement Output Specifications

Explains I (Integer) and F (Floating Point) conversion for output.

Specifying Alphameric Fields in FORMAT

DIMENSION Statement

Explains the DIMENSION statement for allocating storage for arrays.

Writing FORTRAN Statements for Problem Solution

Processing with the FORTRAN Pre-Compiler

Operating Principles

Producing the Object Program

Explains the fundamental steps for creating the object program from source code.

Clearing Core Storage to Zero

Console Switch Settings for Compilation

Loading the FORTRAN Compiler

Explains the procedures for loading the compiler program deck or tape.

Compiling the FORTRAN Source Program

Describes how to initiate compilation of the FORTRAN source program.

Loading FORTRAN Subroutines

Explains how to load subroutine decks or tapes after source program compilation.

Common Source Program Errors During Compilation

Executing the Object Program

Details the procedures for loading and executing the compiled FORTRAN object program.

Inputting Data from the Keyboard During Execution

Using the Trace Feature for Debugging

Explains how to use the trace feature to monitor program flow and check correctness.

Analysis of the FORTRAN Program

FORTRAN Subroutines: Overview and Classification

Introduces FORTRAN subroutines, their types, and available sets.

Floating Point Accumulator (FAC)

FORTRAN Subroutine Linkage Mechanism

Error Analysis of FORTRAN Subroutines

Discusses errors, their codes, and FAC values for FORTRAN subroutines.

FORTRAN Subroutine Error Checks and Codes

Lists subroutine error checks, error codes, and FAC values for error conditions.

Adding Custom Subroutines to FORTRAN

Processor

Processor Subroutine Management

Storage Allocation

Storage Allocation After Compiler Loading

Storage Allocation After Source Program Processing

The FORTRAN Pre-Compiler Program

Operation of the FORTRAN Pre-Compiler

Explains the two-phase operation: Error Analysis and Final Program Summary.

Pre-Compiler Error Code Categories

Categorizes the common errors detected by the Pre-Compiler program.

FORTRAN Statement Number Errors

FORTRAN Transfer Statement Errors

General FORTRAN Statement Errors

Error Analysis Phase

Restart Procedures in Error Analysis

Final Program Summary in Pre-Compiler

Program Switch Settings

Loading the FORTRAN Pre-Compiler Program

Details the steps required to load the FORTRAN Pre-Compiler program.

Processing the Source Program with Pre-Compiler

Explains how to process the source program using the Pre-Compiler.

Pre-Compiler Program Deck Structure

Pre-Compiler Program Tape Structure

Pre-Compiler Tape Data Identification

Duplicating the FORTRAN Pre-Compiler Tape

Appendix A - Summary of 1620 FORTRAN Statements

ACCEPT Statement Summary

ACCEPT TAPE Statement Summary

DIMENSION Statement Summary

Summarizes the DIMENSION statement for array declaration.

DO Statement Summary

Summarizes the DO statement for loop control.

FORMAT Statement Summary

Summarizes the FORMAT statement for data conversion.

GO TO Statement Summary

Computed GO TO Statement Summary

IF Statement Summary

Summarizes the IF statement for conditional logic.

PRINT Statement Summary

Summarizes the PRINT statement for printer output.

PUNCH Statement Summary

PUNCH TAPE Statement Summary

READ Statement Summary

Summarizes the READ statement for card input.

TYPE Statement Summary

Summary of 1620 Operating Principles

1620 Typewriter Input Operations

Manual Data Entry via Typewriter

Typewriter Output Operations

Paper Tape Input Procedures

IBM Tape Punch Operation

IBM 1621 Paper Tape Reader Operation

Card Input

Covers the process of inputting data via punched cards.

IBM 1622 Card Read Punch Overview

Provides an overview of the IBM 1622 Card Read Punch.

1622 Card Feed Motor Control

1622 Card Read Operation

1622 Card Punch Operation

1622 Operator Keys and Lights

1622 Card Reader Controls and Indicators

1622 Card Punch Controls and Indicators

IBM 1443 Printer Overview

Provides an overview of the IBM 1443 printer.

1443 Printer Keys, Lights, and Switches

Details the keys, lights, and switches for operating the 1443 printer.

1443 Printer Start Key Operation

Explains the operation of the 1443 printer's start key.

1443 Printer Stop Key Operation

Details the operation of the 1443 printer's stop key.

1443 Printer Power On Light

1443 Printer Ready Light

Explains the function of the 1443 printer's ready light.

1443 Printer Sync Check Light

Describes the 1443 printer's sync check light and error conditions.

1443 Printer Parity Check Light

Explains the 1443 printer's parity check light indicator.

1443 Printer Form Check Light

1443 Printer End-of-Form Light

1443 Printer Manual Controls

Details the manual controls for operating the 1443 printer.

1443 Character-Set Selection Switch