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.3
The earlier Capcom system board, the original CP System (or CPS-1), while successful, was very vulnerable to bootleggers making 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 ROMs to prevent software piracy. Due to the encryption, the system was never bootlegged until unencrypted program data became available.
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 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.
The B boards hold battery-backed memory containing decryption keys 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 one4 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 emulation was next to impossible. However, in January 2001, the CPS-2 Shock group5 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 images, 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 Andreas Naive (Archived 2013-07-02 at the Wayback Machine6) and Nicola Salmoria. It has been determined that the encryption employs two four-round Feistel ciphers with a 64-bit key.78 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.910
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, 2015.11 Battery replacements ended on February 28, 2019,12 ending all official support of the CP System II hardware and software.
See also: CP System: Technical specifications
Piracy of Intellectual Property on Peer-to-peer Networks. U.S. Government Printing Office. September 26, 2002. p. 141. ISBN 978-0-16-069280-2. 978-0-16-069280-2 ↩
"弊社製品のサービス対応終了に関するご案内". Capcom. 2018-11-12. Retrieved 2024-04-25. https://www.capcom.co.jp/arcade/news/operator/201811.html ↩
"Cover Story: "This Is the Good Time" – Capcom's CPS system brings success to the firm... and offers direction for a troubled video market". RePlay. Vol. 15, no. 7. RePlay Publishing. April 1990. pp. 183–5. 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 ↩
"CPS-2 Shock". http://cps2shock.emu-france.info/suicide.html ↩
"CPS-2 Shock". http://cps2shock.emu-france.info/wip.html ↩
"Notas de Andy". Archived from the original on 2013-07-02. Retrieved 2007-01-04. https://web.archive.org/web/20130702190633/http://andreasnaive.blogspot.com/ ↩
MAME source - cps2crypt.cpp https://github.com/mamedev/mame/blob/master/src/mame/machine/cps2crypt.cpp ↩
Salmoria, Nicola (14 January 2007). "Nicola's MAME Ramblings: CPS2 Getting Closer". http://mamelife.blogspot.com/2007/01/cps2-getting-closer.html ↩
Cruz, Eduardo (30 April 2016). "Arcade Hacker: Important Capcom CPS2 Announcement". http://arcadehacker.blogspot.com/2016/04/important-capcom-cps2-announcement.html ↩
"CPS2 Board Security Successfully Reverse Engineered; Allows Dead Arcade Boards to be Easily Resurrected". 10 May 2016. Archived from the original on 18 May 2016. Retrieved 22 May 2016. 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/ ↩
"弊社基板製品保守サービス業務終了のご案内". Capcom. 2014-09-30. Retrieved 2024-04-25. https://www.capcom.co.jp/arcade/news/operator/20140930.html ↩
"Mame/Cps2.c at master · mamedev/Mame · GitHub". GitHub. Archived from the original on 2015-11-05. Retrieved 2014-11-22. https://web.archive.org/web/20151105142542/https://github.com/mamedev/mame/blob/master/src/mame/drivers/cps2.c ↩
"System 16 - CP System II (CPS2) Hardware (Capcom)". http://www.system16.com/hardware.php?id=795 ↩
"mamedev/mame". GitHub. https://github.com/mamedev/mame/blob/master/src/mame/includes/cps1.h ↩
"HM514260AJ-8 - HM514260AJ8 - Quest Components, Inc. - Electronic Component Distributors - Resistor & Capacitor Distributors - Obsolete Electronic Components - Discrete Semiconductor Distributors - Integrated Circuit Distributors - Quest Components". Archived from the original on November 22, 2014. https://archive.today/20141122235018/http://www.questcomp.com/QuestDetails.aspx?pn=HM514260AJ-8 ↩