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Elastic Work Space For An APL System

IP.com Disclosure Number: IPCOM000052065D
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Alfonseca, M: AUTHOR [+2]

Abstract

This article describes a procedure that gives an APL system access to a work space several times larger than the main memory size of the machine where the APL system is implemented, regardless of its having an operating system supporting virtual storage. The procedure is specially useful in the case of small machines provided with a limited memory size. It can also be applied to large computer systems when several active work spaces are to be simultaneously present in main memory.

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Elastic Work Space For An APL System

This article describes a procedure that gives an APL system access to a work space several times larger than the main memory size of the machine where the APL system is implemented, regardless of its having an operating system supporting virtual storage. The procedure is specially useful in the case of small machines provided with a limited memory size. It can also be applied to large computer systems when several active work spaces are to be simultaneously present in main memory.

The active work space is split into two parts. The first part, which is called the memory work space (MWS), is located in the main storage of the machine. The second one, called the elastic work space extension (EWS), is placed in a fast direct access device, such as a disk unit.

Under normal circumstances, the APL system ignores the existence of EWS and works as if MWS were the only available work space. When a work space full condition arises, the following procedure is followed:

1. A "garbage collection~ i.e., a collection of unused gaps in memory space to allow their combined utilization, is performed.

2. If the work space full condition has subsided, the system goes on working as before.

3. Otherwise, the user-defined APL objects (functions or variables) not currently in use are sent to the EWS, and erased from the MWS, thus freeing the space they were holding. Their logical location in the EWS is stored in the symbol table of the MWS. A new gar...