Content deleted Content added
Matthiaspaul (talk | contribs) →References: improved ref |
Matthiaspaul (talk | contribs) CE, added and improved refs |
||
Line 2:
{{Use dmy dates|date=July 2019|cs1-dates=y}}
{{Use list-defined references|date=July 2022}}
[[File:Overlay Programming.svg|thumb|Schematic]]
In a general computing sense, '''overlaying''' means "the process of transferring a [[Block (data storage)|block]] of program code or other data into [[main memory]], replacing what is already stored".<ref name="OED_2015"/> Overlaying is a [[computer programming|programming]] method that allows programs to be larger than the computer's [[main memory]].<ref name="Butterfield_1986"/> An [[embedded system]] would normally use overlays because of the limitation of [[physical memory]], which is [[internal memory]] for a [[system-on-chip]], and the lack of [[virtual memory]] facilities.
Line 65 ⟶ 66:
In the [[home computer]] era overlays were popular because the operating system and many of the computer systems it ran on lacked virtual memory and had very little RAM by current standards: the original [[IBM PC]] had between 16K and 64K, depending on configuration. Overlays were a popular technique in [[Commodore BASIC]] to load graphics screens.<ref name="Butterfield_1986"/>
"Several [[DOS]] linkers in the 1980s supported [overlays] in a form nearly identical to that used 25 years earlier on mainframe computers."<ref name="Levine_2000"/> [[Binary file]]s containing memory overlays had a de facto standard extension, '''.OVL'''. This file type was used among others by [[WordStar]],<ref name="Mabett_1985"/> [[dBase]],<ref name="Sidnam-Wright-Stevens_1990"/> and the ''Enable'' DOS office automation software package from [[Enable Software, Inc.]] [[Borland]]'s
== See also ==
Line 86 ⟶ 87:
<ref name="IBM_1963_FORTRAN">{{cite manual |title=IBM 7090/7094 Programming Systems – FORTRAN II Programming |id=Form C28-6054-4 File No. 7090-25 |date=August 1963 |work=Systems Reference Library |publisher=[[IBM Corporation]] |publication-place=Poughkeepsie, New York, USA |pages=34–35 |section=Chapter 12: The Chain Job |section-url=http://bitsavers.org/pdf/ibm/7090/C28-6054-4_7090_FORTRANII.pdf#page=34 |url=http://bitsavers.org/pdf/ibm/7090/C28-6054-4_7090_FORTRANII.pdf |access-date=2022-07-10 |url-status=live |archive-url=https://web.archive.org/web/20220315144942/http://bitsavers.org/pdf/ibm/7090/C28-6054-4_7090_FORTRANII.pdf |archive-date=2022-03-15}} (52 pages)</ref>
<ref name="IBM_1963_IBJOB">{{cite manual |title=IBM 7090/7094 Programming Systems – IBJOB Processor – Overlay feature of IBLDR |id=Form C28-6331 File No. 7090-27 |edition=1 |date=May 1963 |work=Systems Reference Library |publisher=[[IBM Corporation]] |publication-place=Poughkeepsie, New York, USA |url=http://bitsavers.org/pdf/ibm/7090/C28-6331_IBLDR_overlay_1963.pdf |access-date=2021-12-26 |url-status=live |archive-url=https://web.archive.org/web/20220315161341/http://bitsavers.org/pdf/ibm/7090/C28-6331_IBLDR_overlay_1963.pdf |archive-date=2022-03-15}} (8 pages)</ref>
<ref name="Mabett_1985">{{cite book |title=Getting started with WordStar, MailMerge + SpellStar |author-first=Alan |author-last=Mabbett |publisher=[[Cambridge University Press]] |date=1985 |isbn=0-521-31805-X}}</ref>
<ref name="Sidnam-Wright-Stevens_1990">{{cite web |title=Ashton-Tate ships dBASE IV Version 1.1 |editor-first1=Liz |editor-last1=Sidnam-Wright |editor-first2=Brad |editor-last2=Stevens |date=1990-07-31 |___location=Torrance, California, USA |publisher=[[Ashton Tate]] |page=2-2-2 |url=http://corphist.computerhistory.org/corphist/documents/doc-4434569d4e6a0.pdf |access-date=2014-02-13 |url-status=dead |archive-url=https://web.archive.org/web/20170404043038/http://corphist.computerhistory.org/corphist/documents/doc-4434569d4e6a0.pdf |archive-date=2017-04-04 |quote=Version 1.1 has a new dynamic Memory Management System (dMMS) that handles overlays more efficiently: the product requires less memory, which results in more applications space availability. […] The product's lower memory requirements of only 450K of RAM provide improved network support because supplemental hardware memory is no longer required to support networks. […] By speeding up areas of dBASE IV that are overlay-dependent, the new dMMS improves performance when working at the Control Center and in programs that use menus and windows.}} (5 pages)</ref>
<ref name="Herschel-Dieterich_2000">{{cite book |title=Turbo Pascal 7.0 |language=de |author-first1=Rudolf |author-last1=Herschel |author-first2=Ernst-Wolfgang |author-last2=Dieterich |edition=2 |publisher={{ill|R. Oldenbourg Verlag|de}} |date=2000 |isbn=3-486-25499-5 |page=249}}</ref>
<ref name="Eßer_2009">{{cite book |title=Betriebssysteme I |chapter=Chapter 6. Speicherverwaltung und Dateisysteme - Teil 5: Nicht-zusammenhangende Speicherzuordnung |language=de |author-first=Hans-Georg |author-last=Eßer |date=June 2009 |publisher=Hochschule München |___location=Munich, Germany |url=http://hm.hgesser.de/bs-ss2009/folien/bs-ss2009-esser-06e-4up.pdf |access-date=2014-02-13 |url-status=live |archive-url=https://web.archive.org/web/20220508155626/http://hm.hgesser.de/bs-ss2009/folien/bs-ss2009-esser-06e-4up.pdf |archive-date=2022-05-08}} (9 pages)</ref>
}}
| |||