Editing CP System II (section)

==History==

Capcom announced the development of the CP System II (or CPS-2) in 1990. They had planned to complete and release the CP System II hardware in 18 months. They also originally had plans for the system to be capable of [[3D graphics]].<ref>{{cite magazine |title=Cover Story: "This Is the Good Time" – Capcom's CPS system brings success to the firm... and offers direction for a troubled video market |magazine=RePlay |date=April 1990 |volume=15 |issue=7 |publisher=RePlay Publishing |pages=183–5 |url=https://archive.org/details/re-play-volume-14-issue-no.-7-april-1990-600dpi/RePlay%20-%20Volume%2014%2C%20Issue%20No.%207%20-%20April%201990/page/183}}</ref>

The earlier Capcom [[Arcade system board|system board]], the original CP System (or CPS-1), while successful, was very vulnerable to bootleggers making [[Counterfeit|unauthorized copies]] of games. In order to rectify the situation, Capcom took the CP System hardware (with [[QSound]]) with minimal changes and employed [[encryption]] on the program [[read-only memory|ROMs]] to prevent [[software piracy]]. Due to the encryption, the system was never bootlegged until unencrypted program data became available.{{cn|date=July 2019}}

The CP System II consists of two separate parts; the ''A'' board, which connects to the [[JAMMA]] harness and contains components common between all CP System II games, and the ''B'' board, which contains the game itself. The relationship between the ''A'' and ''B'' board is very similar to that between a home [[video game console]] and [[ROM cartridge|cartridge]]. CP System II ''A'' and ''B'' boards are color-coded by region, and each board can only be used with its same-colored mate. The exception to this is that the blue and green boards can be used together.{{cn|date=July 2019}}

The ''B'' boards hold battery-backed memory containing [[decryption key]]s needed for the games to run. As time passes, these batteries lose their charge and the games stop functioning, because the CPU cannot execute any code without the decryption keys. This is generally referred to as a "suicide battery". It is possible to bypass the original battery and swap it out with a new one<ref>{{cite web|url=http://cps2shock.emu-france.info/suicide.html|title=CPS-2 Shock|publisher=}}</ref> in-circuit, but this must be done before the original falls below 2V or the keys will be lost. Consequently, the board would just simply die, even if used legally it would not play after a finite amount of time unless a fee was paid to Capcom to replace it.

Due to the heavy encryption, it was believed for a long time that CP System II [[Video game console emulator|emulation]] was next to impossible. However, in January 2001, the CPS-2 Shock group<ref>{{cite web|url=http://cps2shock.emu-france.info/wip.html|title=CPS-2 Shock|publisher=}}</ref> was able to obtain unencrypted program data by hacking into the hardware, which they distributed as [[XOR]] difference tables to produce the unencrypted data from the original [[ROM image]]s, making emulation possible, as well as restoring cartridges that had been erased because of the suicide system.

In January 2007, the encryption method was fully [[reverse-engineered]] by [http://andreasnaive.blogspot.com/ Andreas Naive] ({{Webarchive|url=https://web.archive.org/web/20130702190633/http://andreasnaive.blogspot.com/ |date=2013-07-02 }}<ref>{{cite web|url=http://andreasnaive.blogspot.com/|title=Notas de Andy|publisher=|access-date=2007-01-04|archive-date=2013-07-02|archive-url=https://web.archive.org/web/20130702190633/http://andreasnaive.blogspot.com/|url-status=dead}}</ref>) and [[Nicola Salmoria]]. It has been determined that the encryption employs two four-round [[Feistel cipher]]s with a 64-bit key.<ref>[https://github.com/mamedev/mame/blob/master/src/mame/machine/cps2crypt.cpp MAME source - cps2crypt.cpp<!-- Bot generated title -->]</ref><ref>{{cite web|url=http://mamelife.blogspot.com/2007/01/cps2-getting-closer.html|title=Nicola's MAME Ramblings: CPS2 Getting Closer|first=Nicola|last=Salmoria|date=14 January 2007|publisher=}}</ref> The algorithm was thereafter implemented in this state for all known CPS-2 games in [[MAME]].

In April 2016, Eduardo Cruz, Artemio Urbina and Ian Court announced the successful reverse engineering of Capcom's CP System II security programming, enabling the clean "de-suicide" and restoration of any dead games without hardware modifications.<ref>{{cite web|url=http://arcadehacker.blogspot.com/2016/04/important-capcom-cps2-announcement.html|title=Arcade Hacker: Important Capcom CPS2 Announcement|first=Eduardo|last=Cruz|date=30 April 2016|publisher=}}</ref><ref>{{cite web|url=http://shoryuken.com/2016/05/10/cps2-board-security-successfully-reverse-engineered-allows-dead-arcade-boards-to-be-easily-resurrected/|title=CPS2 Board Security Successfully Reverse Engineered; Allows Dead Arcade Boards to be Easily Resurrected|date=10 May 2016|publisher=|access-date=22 May 2016|archive-date=18 May 2016|archive-url=https://web.archive.org/web/20160518101026/http://shoryuken.com/2016/05/10/cps2-board-security-successfully-reverse-engineered-allows-dead-arcade-boards-to-be-easily-resurrected/|url-status=dead}}</ref>

Capcom ceased manufacturing the CP System II hardware on December 22, 2003, with ''Hyper Street Fighter II'' being the final game released for the hardware. Capcom ended most of the technical support for the hardware and its games on March 31, 2015.<ref name="csend">{{cite web|url=https://www.capcom.co.jp/arcade/news/operator/20140930.html|title=弊社基板製品保守サービス業務終了のご案内|publisher=Capcom|date=2014-09-30|accessdate=2024-04-25}}</ref> Battery replacements ended on February 28, 2019,<ref name="csend2">{{cite web|url=https://www.capcom.co.jp/arcade/news/operator/201811.html|title=弊社製品のサービス対応終了に関するご案内|publisher=Capcom|date=2018-11-12|accessdate=2024-04-25}}</ref> ending all official support of the CP System II hardware and software.