[HN Gopher] Capcom CPS-1 Graphic system study ___________________________________________________________________ Capcom CPS-1 Graphic system study Author : zdw Score : 41 points Date : 2022-02-22 14:24 UTC (1 days ago) (HTM) web link (fabiensanglard.net) (TXT) w3m dump (fabiensanglard.net) | TacticalCoder wrote: | It's always great to read how these worked... | | I'm the proud owner of both a real CPS PCB _and_ a bootleg (but | still vintage) PCB (they go in a arcade cab). If I 'm not | mistaken once you've got a CPS PCB, you can flash any CPS game | you want on it. | | As piracy was rampant with these, Capcom added a battery powering | a Z80 on some CPS boards and if it was ever off, it'd erase the | game. These Z80 are known as "Kabuki Z80". The issue is that... | 25 to 30 years later, all these batteries started failing and | these board would "suicide" themselves. So there are people out | there who "desuicide" (it's the term employed) these boards. | | They're a great piece of history and, well, of course Fabian | Sanglard had to blog about it! | | The Wikipedia page is a cool read too: | | https://en.wikipedia.org/wiki/CP_System | fabiensanglard wrote: | Unfortunately, you cannot flash any game you want on any CPS | PCB. | | A CPS-1 is made of three boards. The CPS-B chip on your B board | changes between games. On later boards, the CPS-B chip remains | the same but it has a battery to store parameters, making it | different. | | If a game attempts to use the CPS-B registers in unintended | way, the screen goes to black and is locked like this. | | The Z-80 battery you mention on CPS-1.5 is to store a private | key that is used to de-crypt the Z-80 instructions. | | And I won't even talk about the CPS-2 because they even | encrypted the 68000 code and shuffled the GFXROM there. | codezero wrote: | Really interesting. I think it's very cool that it only cost | $20M to develop a next generation board that had 10x the power | of a consumer device at the time in an attempt to keep arcades | relevant. It seemed to have worked well until dedicated 3D | cards and the Internet became more consumer friendly, but that | still gave them a good 15 years of lead time it seems. | corysama wrote: | If anyone finds this article even slightly interesting, be sure | to check out the rest of the site! | Bigpet wrote: | Couldn't immediately find a good explanation of what STAR1 and | STAR2 were. Looks like it's 256x256 bitmap that's scrollable and | cycles automatically through a color palette. So you can make the | stars "twinkle" by it just shifting through the palette | | https://github.com/mamedev/mame/blob/master/src/mame/video/c... | | edit: didn't see that "col" also contained an x-offset. So like | (256*16)x256 but presumably "sparse", so I get more where the | "star" idea comes from | allenu wrote: | Thank you for sharing this. That was my first question, i.e. | was the star background hardcoded (or at least statically | generated)? That's super interesting that it was built-in at | all. I suppose so many shooter games had starfield backgrounds | that it made sense at the time to include it. | codezero wrote: | Great post, wanted to let others know you can hover over the | images to see the original reference frame. I didn't realize this | until half way through reading. | kingcharles wrote: | Crap! I need to reread the whole page now. Thanks :) ___________________________________________________________________ (page generated 2022-02-23 23:00 UTC)