EasyManua.ls Logo

IBM 1620 User Manual

IBM 1620
111 pages
To Next Page IconTo Next Page
To Next Page IconTo Next Page
To Previous Page IconTo Previous Page
To Previous Page IconTo Previous Page
Page #30 background imageLoading...
Page #30 background image
Preservation
of
Index Values
Restriction on
Statements
Used in
the
Range
of
a
DO
CONTINUE
Statement
30
In
1620
FORTRAN
it
is possible to transfer into
the
range
of a DO
statement
from
outside its
range
by
either
an
IF
or GO
TO
statement.
(This
cannot
be
done
on
many
other
FORTRAN
programming
systems, and, if there is a possibility
that
the
source
program
will
be
compiled on some
other
FORTRAN
system,
you
should
not
use this
technique. )
If
you write a
statement
to
transfer into
the
range
of a DO from outside of its
range, you
must
understand
that
the
value of
the
index is
not
reset
by
such a
transfer. You
may
use
the
current
value of
the
index or you
may
redefine
the
index
prior to
the
transfer.
If
you
want
to use
the
current
value
of
the
index,
read
the
next
paragraph
carefully,
and
then
review
the
explanation of "Test Value."
The
current
value of
the
index
in
a problem
may
not
be
what
you
think
it
is.
When
the
program
transfers
out
of
the
range of a DO
in
the
normal
manner
(that
is,
when
the
DO becomes satisfied
and
the
program
transfers to
the
next statement
after
the
range),
the
exit is defined as a
normal
exit. After a normal exit from a DO
occurs,
the
value of
the
index is
not
redefined to its original value.
To
determine
the
value of
the
index after a normal exit,
remember
that
after
a loop is completed,
the
index is increased
by
the
increment
before
it
is tested to determine
if
additional
loops
are
to
be
taken.
When
the
program
transfers
out
of
the
range
of a DO
by
an
IF
or
GO
TO
state-
ment,
the
value of
the
index is its
current
value
at
the
time
of
the
transfer.
In
both
types of exits,
the
current
value of
the
index is preserved for any sub-
sequent
use.
If
the
exit occurs
by
a transfer which
is
in
the
range
of
several DO'S,
the
current
values of all
the
indexes controlled
by
those
Do'S
are
preserved for any
subsequent
use.
The
range
of a DO
cannot
contain any
statement
which redefines
the
value of the
index
or
the
value of any of
the
indexing parameters (mJ, mil,
or
mJ)'
The
indexing
of a
DO
statement
must
be
completely
set
before
the
range
of
the
DO is entered.
The
first statement in
the
range
of a DO cannot
be
the
control statement
CONTINUE.
The
CONTINUE
statement
is
sometimes referred to as a "nonexecutable"
statement;
that
is, a
statement
in
the
source program
that
does
not
create
instruc-
tions in
the
object program.
The
nonexecutable instructions
DIMENSION
and
FORMAT
can
be
the
first
statement
in
the
range
of a DO. These two instructions
are
described
later.
The
last statement
in
the
range
of a DO
must
not
be
a
program
transfer state-
ment
(IF
or GO
TO,
etc.)
or
a specification statement
(FORMAT
or
DIMENSION).
This
statement
is
used
as
the
last
statement
in
the
range of a DO
when
the
last state-
ment
would
otherwise
be
a
program
transfer statement
(see
rule
previously given) .
This
statement
does
not
create
any
instructions
in
the
object program.
Format:
I~"_C_O_N_T_I_N_U
__
E_"
______________________________
~
Example:
CONTINUE
~----------------------------------------------~
Consider
the
following table search program which requires a
CONTINUE
state-
ment. This program will scan
the
100-entry array
named
VALUE
until
it
finds an
element which equals
the
value of
the
variable
named
ARG,
then
the
program will
transfer to
statement
20
with
the
value of I available for use.
If
no element in
the
array is
equal
to
the
value of ARG,
the
program
is
transferred to
statement
12.
No
operations
are
performed
by
the
CONTINUE
statement;
the
program
merely con-
tinues
with
the
next sequeritial
statement
following
statement
12.

Table of Contents

Other manuals for IBM 1620

Preview: Manual Of Instruction
Manual Of Instruction12 pages
Question and Answer IconNeed help?

Do you have a question about the IBM 1620 and is the answer not in the manual?

IBM 1620 Specifications

General IconGeneral
CategoryDesktop
ManufacturerIBM
Model1620
Introduced1959
WeightApproximately 1, 000 pounds
Memory20, 000 to 60, 000 digits
ProgrammingFORTRAN, Symbolic Programming System (SPS)
CPUDecimal, variable word length
StorageMagnetic 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

Related product manuals