Arcade Board Homebrew Development?

[Drew Sebastino]

Oops...

[Drew Sebastino]

I just looked up "M92" and got only about 10 results, with none of them being helpful...

Edit: Well, I just noticed MAME.org has a forum... Maybe I'll pester ask the people over there...

[Memblers]

I've thought about messing around with some code on my Millipede game sometime, don't know if I'll get around to doing that though. Pretty nice that the manual includes full schematics and documents all the registers and memory map.

No surprise that I've messed around with Nintendo VS and Playchoice. I made a PC10 board a few years ago, using a CPLD to act as the 'security' chip. I haven't done anything interesting with it, though.

Espozo, I don't think you've mentioned if you have any of these boards you're wanting to work with. If your plan is to develop something and test in MAME first and hope it works on the real hardware later, I predict you may be in a for quite an uphill battle.. The good news is that you can certainly get the hardware and a JAMMA setup. Though I'd be a little concerned if the board has some sort of security features to deal with.

[Drew Sebastino]

Yeah, as of now, I do not have an M92. From what I've heard, It's 2 boards: a "console" one, and a "cartridge" one. However, I've only been able to find a "cartridge" one for some reason, as in I haven't actually found the system yet, unless this is both the game and the system. http://www.ebay.com/itm/Arcade-pcb-boar ... 19fd42e607

[Memblers]

It's hard to tell from the picture in that auction, but it does kinda look like there are screws in the mounting holes on the board, which would indicate that there is something underneath. There pretty much has to be, those pics show it working, yet there aren't any ROMs on the board in the picture. I don't know enough about Irem stuff to tell if that's a legit board or a bootleg though.

Yeah, it seems to be kinda common for the "system" and "game" boards to be separate. The most modern arcade board I own is SF2CE (CPS1), and it's like that too.

[Drew Sebastino]

I really wonder if the guy is selling both boards, because if he is, that seems like a pretty good deal... (I got plenty of money I've saved over birthdays and Christmases.)

Yeah, it seems to be kinda common for the "system" and "game" boards to be separate. The most modern arcade board I own is SF2CE (CPS1), and it's like that too.

About that time period is where I'd have most my games... Like I've said before, the NES is my 3rd favorite console, behind the N64 and the SNES. I just couldn't get into anything like Pac Man. The reason I like the NES the amount I do is because of the latter games that started to appear around 1987, like Castlevania or Contra, which are much more of what I'd consider a game than something like Wrecking Crew.

Anyway, the M92 actually does seem to share a bit of similarities with the CPS1. Both have 3 BGs and I think have only 16x16 sprites, but have a ton of them. I know the M92 does at least. The M92 has a lot of sprites I know. This plane thing is made completely out of sprites:



You know, I know Irem kicked the bucket so they wouldn't have been able to continue, but it is a bit crazy to me how the Neo Geo outlived generally superior hardware, like the CPS2. By about 5 years nonetheless.

Oh yeah, do you want to know one awesome thing about the Irem M92? It has perfect 4:3 aspect ratio. (320x240)

[tepples]

Oh yeah, do you want to know one awesome thing about the Irem M92? It has perfect 4:3 aspect ratio. (320x240)

But does the pixel clock run within 1% of 135/22 = 6.136 MHz? That's what it'd have to do in order to produce perfectly square pixels through a SuperGun. The closest to square pixels that I've found among "standard resolution" (240p class) arcade hardware is the Pac-Man and Galaxian boards, which uses a 768/125 = 6.144 MHz pixel clock at 288x224.

The CPS1, CPS2, and M72 use an 8 MHz pixel clock, which is closer to the 630/77 = 8.19 MHz pixel clock of the NTSC Commodore 64. Pixels on the C64 are three-fourths of a scanline tall.

(See Dot clock rates and sources cited therein.)

[Drew Sebastino]

Hey, I found something that I think is useful, but I don't have the slightest clue as to what I'm looking at: https://github.com/OpenEmu/UME-Core/blo ... ideo/m92.c What programming language is that? C?

Also, I found the page by looking up "irem m92 pixel clock" and it said "Pixel clock is 26.6666MHz (some boards 27MHz??)" Is that even possible?

[Joe]

That is part of the MAME source code that I pointed you towards earlier. (It's a copy being used as a part of OpenEmu.) MAME is written in C and C++, with a lot of macros to abstract away the emulator core.

Arcade machines don't have to adhere to television standards; the only limit is the display hardware. With that said, it's pretty likely that the video hardware divides that frequency to get the pixel clock.