Editing IBM Monochrome Display Adapter (section)

== Use ==
[[File:IBM PC 5150.jpg|thumb|[[IBM 5151]] monitor driven by a Monochrome Display Adapter (MDA)]]
The MDA was released alongside the IBM [[Color Graphics Adapter]], and can be installed alongside the CGA in the same computer. A command included with PC DOS permits switching the primary display between the CGA and MDA cards.<ref>{{Cite web |last=Elliott |first=John |date=April 24, 2011 |title=Dual-Head operation on vintage PCs |url=https://www.seasip.info/VintagePC/dualhead.html |access-date=2020-08-16 |website=John Elliott's homepage}}</ref> Some software like [[Lotus 1-2-3]] supports using both cards at the same time.<ref name="derfler198303">{{cite magazine |url=https://books.google.com/books?id=7wCiNAUEuAMC&pg=RA1-PA187 |title=A Program You Can Count On |magazine=[[PC Magazine]] |date=March 1983 |access-date=2013-10-21 |author-last=Derfler |author-first=Frank J. Jr. |pages=187 |volume=1 |issue=10}}</ref>

Because of the lack of pixel-addressable graphics, MDA owners were unable to play PC games released with graphics support. However, [[Text mode|textmode games]] were released for the PC (including [[text adventures]]) and at least one game, IBM's ''One Hundred And One Monochrome Mazes'', requires MDA.<ref name="manes19840124">{{cite news|author=Manes, Stephen|date=1984-01-24|title=It's Not Easy Being Green|page=391|work=PC Magazine|url=https://books.google.com/books?id=kSzKzjWHeVEC&pg=PA391|access-date=24 October 2013}}</ref> Box-drawing characters made the production of rudimentary graphics practical for early PC game titles, including [[BBS door]] games or titles such as ''[[Castle Adventure]]''.

Another use for the MDA was as a secondary display for [[debugging]]. Applications like [[SoftICE]]<ref>{{Cite book |url=http://softice1.free.fr/docs/NuMega%20-%20Using%20SoftICE.pdf |title=Using SoftICE |publisher=Compuware Corporation |year=1998 |pages=12}}</ref> and the Windows debugger<ref>{{Cite news |last=Glass |first=Brett |date=April 1, 1991 |title=The AT's Shortcomings Force Single-Monitor Programming |pages=62 |work=InfoWorld |url=https://books.google.com/books?id=0FAEAAAAMBAJ&q=debugger%20MDA%20monitor&pg=PA62}}</ref> permitted the simultaneous use of an MDA and another graphics card, with the MDA displaying a debugger interface while the other card was showing the primary display.

=== Disadvantage ===
{{expert|Computing|talk=Disadvantage|date=December 2023}}
A typical 8-bit monochrome card could turn the 16-bit 8 MHz ISA bus into an 8-bit 4 MHz [[PC bus]], which resulted in having the bus bandwidth cut by up to 75%. If the monochrome card was added to the PC as a second card besides a normal [[VGA]] card for debugging purposes, this resulted in slow VGA performance. Microsoft recommended in its ''Writing HOT Games for Microsoft Windows'' (1994) to remove the monochrome card in such a setup for maximum speed of the VGA card.<ref>{{Cite book |url=https://www.tech-insider.org/windows/research/acrobat/940929-a.pdf |title=Writing HOT Games for Microsoft Windows – The Microsoft Game Developers' Handbook |publisher=Microsoft Windows Multimedia |year=1994 |pages=17}}</ref>