MSCDEX

{{Redirect|Microsoft CD-ROM Extensions|Microsoft's extension to the ISO 9660 format|Joliet (file system)}} {{Use dmy dates|date=June 2019|cs1-dates=y}} {{Use list-defined references|date=January 2022}} {{More citations needed|date=October 2025}} {{Infobox software | name = MSCDEX | logo = | screenshot = Windows 98 startup disk screenshot.png | screenshot size = | caption = MSCDEX as seen from a Windows 98 installation CD | developer = Microsoft | released = {{Release year|1986|df=yes}} | latest release version = 2.25 | latest release date = {{Start date and age|1995|df=yes}} | operating system = MS-DOS, Windows | platform = x86 | genre = Command | license = Proprietary commercial software | website = }}

'''MSCDEX''' or '''Microsoft CD-ROM Extensions''' is a software program produced by Microsoft and included with MS-DOS 6.x<ref name="Wolverton_2003"/> and certain versions of Windows to provide CD-ROM support.<ref name="Microsoft_2000_History"/> Earlier versions of MSCDEX since 1986 were installable add-ons for MS-DOS 3.1 and higher.<ref name="Barney_1986"/><ref name="Mace_1986"/>

==Overview== The program is a driver executable which allows MS-DOS programs to recognize, read, and control CD-ROMs using the High Sierra and – since version 2.0 as of 1988 – also the ISO 9660 file systems.<ref name="Johnston_1988"/><ref name="Microsoft_1994_CDEX21"/> This requires the previous loading of an appropriate CD-ROM device driver (example: OAKCDROM.SYS), usually from CONFIG.SYS.

The final version of the MSCDEX program was 2.25,{{cn|date=January 2020|reason=Various editors have changed this to 2.25, 2.95 and 2.96.}} included with Windows 95 and used when creating bootable floppy disks with CD-ROM support. Starting with Windows 95, CD-ROM access became possible through a 32-bit CDFS driver.

The driver uses the Microsoft networks interface in MS-DOS. This is the reason that at least version 3.1 of MS-DOS is required. The driver essentially looks similar to a network drive from the system perspective. It is implemented as a terminate-and-stay-resident program<ref name="Microsoft_1994_CDEX21"/> and an extension to the redirector interface ('''CDEX''').

Datalight ROM-DOS includes an implementation of MSCDEX.<ref name="Datalight_2005_ROM-DOS"/>

==Alternatives== {{anchor|NWCDEX}}Novell DOS 7, Caldera OpenDOS 7.01 and DR-DOS 7.02 and higher provide a functional equivalent to MSCDEX named '''NWCDEX''', which also runs under MS-DOS and PC DOS. It has more flexible load-high capabilities, also allowing to relocate and run in protected mode through DPMS on 286 and higher processors, thereby leaving only a 7 KB stub in conventional or upper memory (in comparison to MSCDEX, which occupies some 16 KB).<ref name="Paul_1997_NWDOSTIP"/> Using EMS with a page frame, NWCDEX can reduce its footprint even down to a few bytes in conventional memory.<ref name="Paul_1997_NWDOSTIP"/> In contrast to MSCDEX, the driver does not depend on undocumented DOS APIs<ref name="Paul_1997_NWDOSTIP"/><ref name="Schulman_1994_Undocumented-DOS"/> and therefore, with a third-party helper tool named '''INSTCDEX''',<ref name="Paul_1997_NWDOSTIP"/><ref name="Paul_1997_INSTCDEX"/><ref name="Paul_1997_NWCDEX"/><ref name="Paul_1997_OD-A3"/> can be loaded via {{mono|INSTALL}} statements and be fully functional in CONFIG.SYS thereby increasing chances to load the driver high and, under these operating systems, allow to load other drivers not only from hard disk but also from CD-ROM while the operating system is still processing CONFIG.SYS.<ref name="Paul_1997_NWDOSTIP"/><ref name="Paul_1997_OD-A3"/> An alternative solution, but less flexible, some versions of DR-DOS offer to delay the installation of a driver in CONFIG.SYS until after the DOS data segment relocation via <code>[[INSTALLLAST (CONFIG.SYS directive)|INSTALLLAST]]</code>.

{{anchor|IMSCDEX}}Based on NWCDEX, IMS REAL/32, a successor to Novell's Multiuser DOS and Digital Research's Concurrent DOS, provides a similar driver named '''IMSCDEX'''.<ref name="Paul_1997_NWDOSTIP"/>

{{anchor|CLOAKING}}A cloaked variant of MSCDEX was provided as part of Helix Software's Multimedia Cloaking product. It uses Cloaking to relocate and run in protected mode on 386 and higher processors.

{{anchor|CORELCDX}}Corel offered '''CORELCDX.COM''' as alternative to MSCDEX.<ref name="Corel"/>

{{anchor|SHSUCDEX}}There's a free alternative called '''SHSUCDX'''<ref name="BOOTCD"/> that is used with the IDE/ATA driver UIDE.SYS<ref name="UIDE.SYS"/> first released in 2005.<ref name="SHSUCDEX"/> It is often used with FreeDOS and works with other DOSes as well.

In 1998, Caldera provided a DRFAT32 driver for DR-DOS to dynamically mount and unmount FAT32 volumes on DOS versions otherwise not natively supporting FAT32. DRFAT32 uses a variation and extension of the CDEX API in order to achieve this and work with older DOS versions.<ref name="Brown_RBIL"/>

==See also== * List of DOS commands

==References== {{Reflist|refs= <ref name="Wolverton_2003">{{Cite book |author-last=Wolverton |author-first=Van |title=Running MS-DOS Version 6.22 |version=20th Anniversary Edition |edition=6th revised |date=2003 |publisher=Microsoft Press |isbn=0-7356-1812-7}}</ref> <ref name="Microsoft_2000_History">{{cite web |title=History of Microsoft MS-DOS CD-ROM Extensions (MSCDEX) |publisher=Microsoft Corporation |date=2000-01-18 |id=Q123408 |work=Microsoft Product Support Services |url=http://support.microsoft.com/kb/q123408/ |access-date=2007-11-24 |url-status=dead |archive-url=https://web.archive.org/web/20080708235428/http://support.microsoft.com/kb/q123408/ |archive-date=2008-07-08}} [https://www.infania.net/ms6kb/Q123408.htm] (NB. Has information on MSCDEX versions 2.1, 2.2, 2.21, 2.22, 2.23.)</ref> <ref name="Barney_1986">{{cite journal |title=Microsoft lets micros read CD-ROMs |journal=Computerworld |author-first=Douglas |author-last=Barney |date=1986-09-22 |page=13 |url=https://books.google.com/books?id=vrrvpxLbx7UC&pg=PA13 |access-date=2016-11-18}}</ref> <ref name="Mace_1986">{{cite journal |title=Extensions to MS-DOS Run CD-ROM |author-first=Scott |author-last=Mace |journal=InfoWorld |volume=8 |issue=38 |date=1986-09-22 |pages=1, 8 |url=https://books.google.com/books?id=ZS8EAAAAMBAJ&pg=PA1 |access-date=2016-11-09}}</ref> <ref name="Paul_1997_OD-A3">{{cite web |author-first=Matthias R. |author-last=Paul |title=Caldera OpenDOS 7.01/7.02 Update Alpha 3 IBMBIO.COM README.TXT |url=http://www.uni-bonn.de/~uzs180/download/ibmbioa3.zip |date=1997-10-02 |access-date=2009-03-29 |url-status=dead |archive-url=https://web.archive.org/web/20031004074600/http://www-student.informatik.uni-bonn.de/~frinke/ibmbioa3.zip |archive-date=2003-10-04}} [https://web.archive.org/web/20181225154705/http://mirror.macintosharchive.org/max1zzz.co.uk/+Windows%20&%20DOS/DOS/System/Novell/Support/Bins/Op702src.zip]</ref> <ref name="Brown_RBIL">Ralf D. Brown. ''Ralf Brown's Interrupt List'', INTER61 as of 2000-07-16 ([https://www.cs.cmu.edu/~ralf/files.html])</ref> <ref name="Corel">{{citation |title=Mention of CORELCDX|url=http://files.mpoli.fi/unpacked/drivers_1/cd/teac/4x/teac4.zip/readme.txt|access-date=2023-12-31}}</ref> <ref name="Johnston_1988">{{cite journal |url=https://books.google.com/books?id=CD8EAAAAMBAJ&pg=PA20 |journal=InfoWorld |date=1988-03-07 |page=198 |author-first=Stuart J. |author-last=Johnston |title=Microsoft Steals Show At Its CD ROM Meeting - Firm Unveils Two Business Titles}}</ref> <ref name="Microsoft_1994_CDEX21">{{cite web |title=Microsoft MS-DOS CD-ROM Extensions 2.1 |version=Version 2.10 Beta |date=1994-03-16 |orig-year=1992-05-30 |type=MSCDEX21.DOC |id=000080010-100-O00-1186 |publisher=Microsoft |url=http://cybermax.tripod.com/mscdex.txt |access-date=2018-05-11 |url-status=live |archive-url=https://web.archive.org/web/20180511084215/http://cybermax.tripod.com/mscdex.txt |archive-date=2018-05-11}} [https://web.archive.org/web/20180511085639/http://ftp.lyx.org/pub/pc/garbo/windows/doc/mscdex21.zip]</ref> <ref name="Paul_1997_NWDOSTIP">{{cite book |title=NWDOS-TIPs — Tips & Tricks rund um Novell DOS 7, mit Blick auf undokumentierte Details, Bugs und Workarounds |work=MPDOSTIP |author-first=Matthias R. |author-last=Paul |date=1997-07-30 |orig-year=1994-05-01 |edition=3 |version=Release 157 |language=de |url=http://www.antonis.de/dos/dos-tuts/mpdostip/html/nwdostip.htm |access-date=2014-08-06 |url-status=live |archive-url=https://web.archive.org/web/20161104235829/http://www.antonis.de/dos/dos-tuts/mpdostip/html/nwdostip.htm |archive-date=2016-11-04}} (NB. NWDOSTIP.TXT is a comprehensive work on Novell DOS 7 and OpenDOS 7.01, including the description of many undocumented features and internals. It is part of the author's yet larger MPDOSTIP.ZIP collection maintained up to 2001 and distributed on many sites at the time. The provided link points to a HTML-converted older version of the NWDOSTIP.TXT file.) [https://web.archive.org/web/20190601152204/https://www.sac.sk/download/text/mpdostip.zip]</ref> <ref name="Schulman_1994_Undocumented-DOS">{{cite book |author-first1=Andrew |author-last1=Schulman |author-first2=Ralf D. |author-last2=Brown |author-link2=Ralf D. Brown |author-first3=David |author-last3=Maxey |author-first4=Raymond J. |author-last4=Michels |author-first5=Jim |author-last5=Kyle |title=Undocumented DOS: A programmer's guide to reserved MS-DOS functions and data structures - expanded to include MS-DOS 6, Novell DOS and Windows 3.1 |publisher=Addison Wesley |edition=2 |date=1994 |orig-year=November 1993 |isbn=0-201-63287-X |url=https://archive.org/details/undocumenteddosp00andr_0}} (xviii+856+vi pages, 3.5"-floppy) Errata: [https://web.archive.org/web/20190417215556/https://www.cs.cmu.edu/afs/cs/user/ralf/pub/books/UndocumentedDOS/errata.ud2][https://web.archive.org/web/20190417212906/https://www.pcjs.org/pubs/pc/programming/Undocumented_DOS/#errata-2nd-edition]</ref> <ref name="BOOTCD">{{cite web |title=Command: shsucdx |date=2008 |orig-year=2003 |author-first1=Robert |author-last1=Platt |author-first2=W. |author-last2=Spiegl |work=FreeDOS Spec Command HOWTO |url=http://help.fdos.org/en/hhstndrd/base/shsucdx.htm |access-date=2018-05-11 |url-status=live |archive-url=https://web.archive.org/web/20180511081140/http://help.fdos.org/en/hhstndrd/base/shsucdx.htm |archive-date=2018-05-11}}</ref> <ref name="UIDE.SYS">{{cite web |title=Command: uide.sys / uidejr.sys |date=2011 |orig-year=2007 |author-first1=Jack |author-last1=Ellis |author-first2=W. |author-last2=Spiegl |work=FreeDOS Spec Command HOWTO |url=http://www.bootablecd.de/FreeDOS/help/en/hhstndrd/base/uide.htm |access-date=2018-05-11 |url-status=live |archive-url=https://web.archive.org/web/20180511081202/http://www.bootablecd.de/FreeDOS/help/en/hhstndrd/base/uide.htm |archive-date=2018-05-11}}</ref> <ref name="SHSUCDEX">{{cite web |title=SHSUCDX V3.03A CD-ROM Interface Driver |id=SHCDX33A.ZIP |date=2005-12-26 |url=http://johnson.tmfc.net/dos/shsucdx.html |url-status=dead |archive-url=https://web.archive.org/web/20061012083434/http://johnson.tmfc.net/dos/shsucdx.html |archive-date=2006-10-12}}</ref> <ref name="Paul_1997_INSTCDEX">{{cite web |title=INSTCDEX v2.12 |author-first=Matthias R. |author-last=Paul |date=1997-03-03 |orig-year=1996 |url=http://www.uni-bonn.de:80/~uzs180/mpdokeng.html#M.INSTCDEX |url-status=dead |archive-url=https://web.archive.org/web/20090215001349/http://www.uni-bonn.de/~uzs180/mpdokeng.html#M.INSTCDEX |archive-date=2009-02-15 |quote=[…] load CD-ROM drivers like NWCDEX.EXE/MSCDEX.EXE in CONFIG.SYS by using INSTCDEX […] more flexibility […] loading order of drivers […] more free UMB-RAM during installation […] better highloading memory consuming redirector drivers […] install […] other drivers […] from CD-ROM during execution of CONFIG.SYS […] setting the local CD-ROM flag […] |access-date=2018-07-16}}</ref> <ref name="Paul_1997_NWCDEX">{{cite web |title=NWCDEX |author-first=Matthias R. |author-last=Paul |date=1997-06-26 |work=OpenDOS |url=http://www.delorie.com/opendos//archives/browse.cgi?p=opendos/1997/06/26/06:13:28 |access-date=2018-05-10 |url-status=live |archive-url=https://web.archive.org/web/20180510211627/http://www.delorie.com/opendos//archives/browse.cgi?p=opendos%2F1997%2F06%2F26%2F06%3A13%3A28 |archive-date=2018-05-10 |quote=[…] Since Novell DOS the pre-CDS […] is an internal array containing 26 entries located at the upper end of the conventional memory, although the lastdrive entries in SYSVARS only report a lower value. LASTDRIVE= is one of those directives taking effect only *after* CONFIG.SYS, and the CDS array will be moved to its target position and will be reduced down to the LASTDRIVE= (or other minimum) or will be expanded up to 32 entries. […] INSTCDEX […] free already assigned drive slots for NWCDEX and thus allows NWCDEX to load in CONFIG.SYS. However, it will be unlinked after CONFIG.SYS, since the CDS-array is moved. INSTCDEX also provides means to save the status of the CDS-entry in CONFIG.SYS and relink […] NWCDEX to the new CDS in AUTOEXEC.BAT. […]}}</ref> <ref name="Datalight_2005_ROM-DOS">{{cite web |title=Datalight ROM-DOS User's Guide |date=April 2005 |publisher=Datalight, Inc. |id=Part No. 3010-0200-0716 |url=https://www.datalight.com/assets/files/ROM-DOS_Users_Guide.pdf |access-date=2021-01-02 |url-status=live |archive-url=https://web.archive.org/web/20211206062213/https://www.datalight.com/assets/files/ROM-DOS_Users_Guide.pdf |archive-date=2021-12-06}} (268 pages)</ref> }}

==Further reading== * {{Cite web |title=MS-DOS CD-ROM Extensions 2.2 Information Pack |id=DR0498.EXE |publisher=Microsoft |date=1991-11-01 |url=http://ftpmirror.your.org/pub/misc/ftp.microsoft.com/Softlib/MSLFILES/DR0498.EXE |access-date=2018-05-11 |url-status=live |archive-url=https://web.archive.org/web/20180511080837/http://ftpmirror.your.org/pub/misc/ftp.microsoft.com/Softlib/MSLFILES/DR0498.EXE |archive-date=2018-05-11}} (Self-extracting archive, includes ''Microsoft MS-DOS CD-ROM Extensions Hardware-Dependent Device Driver Specification'') * {{Cite web |title=Command-Line Switches for MSCDEX.EXE |publisher=Microsoft |date=2007-01-18 |version=2.4 |id=KB87165, Q87165 |url=http://support.microsoft.com/kb/87165 |url-status=dead |archive-url=https://web.archive.org/web/20071117234429/http://support.microsoft.com/kb/87165 |archive-date=2007-11-17}} * {{Cite web |title=MSCDEX - Examples |url=http://2dos.homepage.dk/batutil/help/MSCDEX_E.HTM |url-status=dead |archive-url=https://web.archive.org/web/20071125174303/http://2dos.homepage.dk/batutil/help/MSCDEX_E.HTM |archive-date=2007-11-25}} * {{Cite book |author-last=Cooper |author-first=Jim |title=Using MS-DOS 6.22 |version=Special Edition |edition=3 |date=2001 |publisher=Que Publishing |isbn=978-0-7897-2573-8}} * {{Cite book |author-first1=Tim |author-last1=O'Reilly |author-link1=Tim O'Reilly |author-first2=Troy |author-last2=Mott |author-first3=Walter |author-last3=Glenn |date=1999 |title=Windows 98 in a Nutshell: A Desktop Quick Reference |publisher=O'Reilly |isbn=978-1-56592-486-4 |url=https://archive.org/details/windows98innutsh00orei}}

==External links== {{Wikibooks|Guide to Windows Commands}} * [https://www.computerhope.com/mscdex.htm MS-DOS and Windows command line MSCDEX command]

Category:External DOS commands Category:Windows commands