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Modification of Programs in Disk Core Image Format

IP.com Disclosure Number: IPCOM000077607D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Loevenbruck, A: AUTHOR

Abstract

When emulating a 1130 program in DCI format (Disk Core Image Format) on IBM system 370 a method is proposed to search, retrieve and locate the address of subroutines. A transfer vector table contains pointers to the relative addresses in the program where all subroutines are imbedded.

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Modification of Programs in Disk Core Image Format

When emulating a 1130 program in DCI format (Disk Core Image Format) on IBM system 370 a method is proposed to search, retrieve and locate the address of subroutines. A transfer vector table contains pointers to the relative addresses in the program where all subroutines are imbedded.

The "subroutine substitution" technique currently planned for emulating the IBM 1130 Disk Monitor Systems on S/370, requires some modifications to be made on the 1130 user cartridges. A special program must be developed for this purpose.

This program will replace the first executable instruction of each 1130 input- output subroutine by a special instruction, which, when encountered by the emulator, will enable the corresponding function to be executed by the S/370 program.

However, a technical difficulty may appear: a given input-output subroutine may be present at different locations on the cartridge: 1) In the system library - only once

2) Imbedded in the middle of one or several user programs, when

these programs are stored on the cartridge in Disk Core

Storage format.

If it is very easy to localize the input-output subroutines in the System Library, it is more difficult to localize the subroutines in a program in DCI format.

A general solution of the program would be to search in the program, a given sequence of instructions characteristic of a given input-output subroutine. An obvious disadvantage of this solution is its poor p...