View source for DOS/4G

{{Multiple issues|
{{primary sources|date=February 2015}}
{{citation style|date=May 2019}}
}}
{{Infobox software
| name                    = DOS/4G
| logo                    = DOS4GLogo.png
| screenshot              = DOS4GWbanner.svg
| developer               = [[Tenberry Software]]
| latest release version  = 2.01
| latest release date     = {{Start date and age|1996|04|03}}<ref name=rn4g>{{cite web |url=http://www.tenberry.com/dos4g/rn4g.html |archive-url=https://web.archive.org/web/20180507222545/http://www.tenberry.com/dos4g/rn4g.html |url-status=dead |archive-date=2018-05-07 |title=DOS/4G Release Notes}}</ref>
| discontinued            = yes
| operating system        = [[DOS]]
| platform                = [[IA-32]]
| genre                   = [[DOS extender]]
| license                 = [[Proprietary software|Proprietary]]
| website                 = {{URL|https://web.archive.org/web/20180628103312/tenberry.com/dos4g}}
}}
'''DOS/4G''' is a [[32-bit]] [[DOS extender]] developed by [[Rational Systems]] (later [[Tenberry Software]]).<ref>[https://groups.google.com/g/alt.msdos.programmer/c/WznGcFPdHgs/m/KKDnGT-7QAsJ DOS4/GW Is it free? Can you distribute it?]</ref> It allows [[DOS]] programs to eliminate the 640 [[kilobyte|KB]] [[conventional memory]] limit by addressing up to 64<ref>[https://web.archive.org/web/20180609030717/http://www.tenberry.com/dos4g/faq/memory.html#02 DOS4G FAQ]</ref> [[megabyte|MB]] of [[extended memory]] on [[Intel 80386]] and above machines.
== Features ==
Functioning as a highly flexible and reusable memory extension library, DOS/4G allowed programmers to access extended memory without writing specialized code. It embeds itself in the executable file at [[Linker (computing)|linking]] time and executes before main application code, so usually DOS/4G initialization messages show up at launch.  It can in principle operate within [[MS-DOS]], [[PC DOS]], [[DR-DOS]] and other DOS clones, the DOS boxes of [[OS/2]], [[Microsoft Windows]], [[Windows NT]] and [[Windows 95]], and DOS emulators such as [[DOSBox]]. However, in practice few DOS/4G games or other applications will run on non-DOS-based versions of [[Windows]], including [[Windows NT]], [[Windows 2000]] and [[Windows XP]], since none of these allow direct access to the hardware as was used for display rendering in those days.
== History ==
'''DOS/4GW''' 1.95 was a free limited edition of DOS/4G and was included with the [[Watcom C compiler]] with a commercial re-distribution license. It was made widely popular by computer games like ''[[Doom (1993 video game)|Doom]] or [[Tomb Raider (1996 video game)|Tomb Raider]]''.
Initial versions of DOS/4G had trouble with secondary [[DMA channel]]s on the [[ISA bus]], which prevented 16-bit devices like [[Gravis Ultrasound]] series from normally functioning; Gravis even had to develop PREPGAME, a patch utility which updated the game executable with a new version 1.97 to fix the incompatibility.
In case of problems, DOS/4G or DOS/4GW can be replaced with the newer and free [[DOS/32]]; a patch utility can even replace DOS/4G code embedded inside a compiled executable file.<ref>[https://www.dosbox.com/wiki/TOOLS:DOS32A TOOLS:DOS32A - DOSBoxWiki]</ref>
== See also ==
* [[DOS/32]]
* [[DOS Protected Mode Interface]] (DPMI)
* [[DOS API]]
== References ==
{{Reflist}}
== External links ==
* [https://web.archive.org/web/20180630153306/http://www.tenberry.com/dos4g/faq/index.html DOS/4GW FAQ]
{{DEFAULTSORT:DOS 4G}}
[[Category:DOS extenders]]
[[Category:DOS/4GW games| ]]
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