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ISAM for ND-100/ND-500

ND 210073/210343

    +-------------------+
    |                   |
    |     ISAM FILES    |
    |                   |
    +-------------------+
           /      \
          /        \
    +--------+   +--------+
    |        |   |        |
    |        |   |        |
    +--------+   +--------+

ND
Norsk Data

Scanned by Jonny Oddene for Sintran Data © 2021

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ISAM for ND-100/ND-500

INTRODUCTION

ISAM — Indexed Sequential Access Method — for disk storage and retrieval of data may be used from FORTRAN, PLANC and PASCAL. It is included in COBOL. Records may be retrieved by the aid of an index (i.e., key) or in sequential order. ISAM is call-oriented, which means that ISAM services are performed by calling routines from the ISAM library.

An ISAM file is usually located on two SINTRAN files; the index part on one file, the data part on another. Optionally an ISAM file may be placed on one SINTRAN file.

FEATURES

  • Design is based on the ANSI-74 COBOL standard.
  • Maximum number of keys in one ISAM file may be as large as 64. All may have duplicates.
  • Keys may overlap each other, and group keys are allowed.
  • All key values may be modified by the REWRITE call.
  • Maximum number of records 2^24 (i.e., no practical limitation).
  • Maximum record length is 32 K bytes.
  • Maximum key length is 240 bytes.
  • Fixed or variable record length.
  • An ISAM file may be opened in four different modi:
    • Single-user buffered I/O.
    • Single-user buffered input, immediate output.
    • Multiuser buffered input, immediate output, automatic unlock.
    • Multiuser buffered input, immediate output, manual unlock.
  • ISAM file structure may be modified at runtime.
  • ISAM file consistency may be checked and if necessary restored at runtime.
  • The data records may be accessed either via the index tables or directly using the record number.
  • ND-500 version at least 4 times faster than the ND-100 version.
  • ISAM file compatibility ND-100 — ND-500.

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ISAM for ND-100/ND-500

PRODUCT DESCRIPTION

ISAM consists of 4 modules:

  • ISAM library
  • ISAM service program
  • ISAM interactive
  • ISAM multiuser supervisor

ISAM library contains all ISAM routines.

ISAM service program is a user-friendly interactive program including the following service functions:

  • Convert a SINTRAN file into an ISAM file.
  • Modify the ISAM file structure, i.e. create/delete keys.
  • Reset the ISAM error flag.
  • Verify the consistency of an ISAM file.
  • Unload/load an existing ISAM file.
  • Build the index part from the data part.
  • Estimate the size of the index part of the ISAM file.

ISAM interactive is a user-friendly program to assist users in the easy manipulation of ISAM files. This means that data can be stored/retrieved/modified/deleted interactively without writing special programs. All the ISAM library routines are available.

ISAM multiuser supervisor supervises an ISAM process, i.e., it resolves the currency problems that arise when several programs access the same ISAM files concurrently.

DOCUMENTATION

ND Indexed Sequential Access Method
Reference Manual .................. ND-60.108.5 Rev. A EN.