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Modular Programming Techniques

IP.com Disclosure Number: IPCOM000080586D
Original Publication Date: 1974-Jan-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Bouillot: AUTHOR

Abstract

In order to improve the handling of pages and modules by a computer operating according to the modular concept, a new register (Modular Address Register) is added to the computer and new instructions allow, respectively, branching to the first instruction of a module, and to return to a given point after the module has been executed.

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Modular Programming Techniques

In order to improve the handling of pages and modules by a computer operating according to the modular concept, a new register (Modular Address Register) is added to the computer and new instructions allow, respectively, branching to the first instruction of a module, and to return to a given point after the module has been executed.

Generally, handling of pages and modules is performed by interpreter sequences. This system presents some disadvantages: - CPU load is increased, because transit from one module to another requires a lot of instructions to be run in the

interpreter routines. - Modules exits have to specify by what they are followed in the page (another module , a subpage or a page) and this is

a restriction for the flexibility in page writing. - A register must be reserved to handle the module address and has to be saved and restored if used in modules.

Interpreter coding form must be used on only one

interruption level, because the interpreter cannot allow

reentrance from several interruption levels.

The concept of pages and modules can be improved if, instead of handling them by interpreter sequences, they are handled by special instructions.

Since the IAR (Instruction Address Register) allows the performance of sequential operations of instructions, the MAR (Modular Address Register) is a register which will perform operations on modules, pages and subpages.

This new register works on the Indirect Addressing Mode, it contains the address of the store location from where a module is called. That register is modified only by the new instructions, which perform branching to and from modules and pages. These new instructions (BM and SEQn) are described hereinafter, and their application to the handling of pages and subpages by an IBM 1800 computer is explained. A/- BM (Branch to a Module).

When from a given address in storage (7000 in the given example) it is requested to run a module, the first instruction of which being in any location in store (8000 in the example), what is to be done with addresses is: - to branch to the first instruction of the module (8000), - to record the address from where the module was called (7000), and - once the module is executed, to retu...