Editing Sega CD (section)

==Technical specifications==
[[File:Sega-CD-Base-Mk2-Inside-V1-01.jpg|thumb|right|The motherboard and CD laser assembly to a model 2 Sega CD]]
The Sega CD can only be used in conjunction with a Genesis system, attaching through an expansion slot on the side of the main console.<ref>{{Cite magazine|date=February 1993|title=Mega-CD|magazine=[[Computer and Video Games]]|issue=135|page=16}}</ref> It requires its own power supply.<ref name="specs" /> A core feature of the Sega CD is the increase in data storage by its games being CD-ROMs; whereas [[ROM cartridge]]s of the day typically contained 8 to 16 megabits of data, a CD-ROM disc can hold more than 640 [[megabyte]]s of data, more than 320 times the storage of a Genesis cartridge. This increase in storage allows the Sega CD to play [[FMV game]]s.<ref name="segacd" /> In addition to playing its own library of games in CD-ROM format, the Sega CD can also play compact discs and [[karaoke]] CD+G discs, and can be used in conjunction with the 32X to play [[32-bit]] games that use both add-ons. The second model, also known as the Sega CD 2, includes a steel joining plate to be screwed into the bottom of the Genesis and an extension spacer to work with the [[Sega Genesis#Variations|original Genesis model]].<ref name="specs">{{cite book|title=Sega CD instruction manual (model 2)|publisher=Sega of America, Inc.|year=1993}}</ref>

The main [[CPU]] of the Sega CD is a 12.5&nbsp;[[MHz]] [[16-bit]] Motorola 68000 processor,<ref name="RetroGamer">{{cite magazine|author=Birch, Aaron|title=Next Level Gaming: Sega Mega-CD|magazine=[[Retro Gamer]]|issue=17|year=2005|pages=36–42}}</ref><ref>{{cite web|url=http://sega.jp/fb/segahard/mcd/data.html|title=Mega-CD data|publisher=Sega Corporation|language=ja|access-date=March 24, 2014|url-status=live|archive-url=https://web.archive.org/web/20131016142854/http://sega.jp/fb/segahard/mcd/data.html|archive-date=October 16, 2013}}</ref> which runs 5&nbsp;MHz faster than the Genesis processor.<ref name="AllgameCD" /> It contains 1&nbsp;Mbit of [[booting|boot]] [[ROM]], allocated for the CD game [[BIOS]], CD player software, and compatibility with CD+G discs. 6.5&nbsp;Mbit of RAM is allocated to data for programs, pictures, and sounds; 128&nbsp;Kbit to CD-ROM data [[cache memory]]; and an additional 64&nbsp;Kbit is allocated as the backup memory.<ref name="specs" /><ref name=":2">{{Cite magazine|date=September 1993|title=Sega Mega-CD II: Retour vers le futur|magazine=Player One|language=French|issue=34|page=53}}</ref> Additional backup memory in the form of a 1&nbsp;Mbit Backup RAM Cartridge was also available as a separate purchase, released near the end of the system's life.<ref>{{cite magazine|title=Saved by the Cart|magazine=[[GamePro]]|issue=83|date=August 1995|page=108}}</ref><ref>{{cite web|url=https://sega.jp/fb/segahard/mcd/backup.html|language=Japanese|accessdate=December 12, 2021|title=Mega CD RAM|publisher=[[Sega Corporation]]|archive-date=October 20, 2020|archive-url=https://web.archive.org/web/20201020092507/https://sega.jp/fb/segahard/mcd/backup.html|url-status=live}}</ref> The graphics chip is a custom [[ASIC]],<ref name=":2" /> and can perform similarly to the SNES's [[Mode 7]], but with the ability to handle more objects at the same time.<ref name=":0" /> Audio is supplied through the Ricoh RF5C164, and two [[RCA connector|RCA pin jacks]] allow the Sega CD to output stereophonic sound separate from the Genesis. Combining stereo sound from a Genesis to either version of the Sega CD requires a cable between the Genesis's headphone jack and an input jack on the back of the CD unit. This is not required for the second model of the Genesis.<ref name=":0" /><ref name="specs" /> Sega released an additional accessory to be used with the Sega CD for karaoke, including a microphone input and various sound controls.<ref>{{cite web|url=https://sega.jp/fb/segahard/mcd/karaoke.html|language=Japanese|title=Mega CD Karaoke|publisher=[[Sega Corporation]]|accessdate=December 12, 2021|archive-date=November 15, 2020|archive-url=https://web.archive.org/web/20201115021909/https://sega.jp/fb/segahard/mcd/karaoke.html|url-status=live}}</ref>