1 (edited by R9_Rider 2015-10-29 11:33:42)

Topic: Irem M72 Custom ICs

Hello, this is Allen. I'm looking to create a CPLD/FPGA implementation for the M72 custom chips.

For example, in the R-Type schematics and parts list. It mentions parts like the KNA71H010, the KNA65005-17, and other parts with a prefix of "KNA".

Now, research tells me that these custom chips are popular with Irem's games, at least the M72 ones, and that they are probably gate arrays with the exception of one, which may be a DAC or a companion to a DAC that outputs analog RGB.

Being somebody experienced with creating FPGA replacements to custom chips, I want to know where to start.

I can't really use the FPGA DIN of Wolfgang's because all of these chips are either packaged in DINs with 48+ pins or flat square packages.

The R-Type Schematics mentioned in the operation manual for the US cabs linked here has separate schematics regarding the use of said KNA chips scattered sporatically between pages 37-56, and the parts list in the pages 24-28 show all the KNA parts among every other part. In the schematics, it does mention that most of these KNA parts are mostly 48 or 64 pin DINS (DIP and S-DIP), with one 40 pin square package that is probably used as/with a DAC generating video output in the last page of the manual. There's also this links which shows detailed pictures of the R-Type board, where you can see better (especially with the M72-A-C board) that the big DILs (48-64 pin) are usually KNA parts.

I was thinking at some point of getting a bootleg of a M72 game (probably R-Type) or getting somebody to post detailed pics of the parts there to see what they did to recreate the original custom chip's functionalities. I have a link for a small discussion about these chips that is also interesting.

Also the M72 boards have PAL/GAL chips used via certain PLD binary code programmed into them. Some of them are used globally across games from the M72 and its direct variants (M81, M82?, M84), and some seem to be exclusive to certain games. Even then, there are a few such chips that are undumped, at least the M72-A-8L and the M72-A-9L from the main R-Type board, which can be seen here.

A list of dumps of arcade PLD data can be found here, and a few dumped files pertaining to the M72 and variants can be found below:

M72-A-4D (Global?)
M72-A-3D (Global?)
MIF-C-3F/TOM-C-3F (Image Fight, Tonma)
NIN-C-3F/MH-C-3F (Ninja Spirit, Mr. Heli)
XM-C-3F (X-Multiply)
M72-R-3A (R-Type)

Here's a japanese site and youtube videos where somebody made a PCB emulating/simulating? the M72 using a FPGA and a Nec V30HL:

Youtube demonstration part 1 (has a bunch of japanese text explaining the hardware of the original M72 and his design): https://www.youtube.com/watch?v=x41NtQmzZnw
Youtube demonstration part 2 (Demonstrates it being used in sample games): https://www.youtube.com/watch?v=nfi2mCvVKIY
The creator's website/wiki for the project: http://iremm72.wiki.fc2.com/

As they are all in japanese, I'll need somebody to translate them, especially the videos whose subtitles can't be translated by Google translate like his program can.

EDIT: Fixed links.
EDIT: For some reason the PLD links aren't working properly, so you'll have to copy and paste the links with the http:// prefix. At least, that got the links to work. Failing that, the pld dump site should have them available by searching 'M72' on the search bar.

Re: Irem M72 Custom ICs

Excellent R9. I am Really interested in getting R-Type running - I actually bought a board a few years ago to do some reverse engineering on.

I'll have a read through the links this evening.


Re: Irem M72 Custom ICs

Hello again. Has there been any work done regarding the custom KNA chips since last year?

Re: Irem M72 Custom ICs

Not that I know of sadly

Re: Irem M72 Custom ICs

I would like to confirm that the DAC that outputs video pixels is not a KNA chip, though the actual DAC does get its digital input from a KNA chip (specifically the 60-pin flat KNA91H014).

Looking back at the linked operation manual, at the last page even, the DAC is basically a set of resistor arrays, one for each color, that converts the digital color bits to analog, then takes the analog output through EMI filters and finally reaching the JAMMA edge connector.

Have you looked into the links at any point or do you even remember at this point?

Re: Irem M72 Custom ICs

I haven't found much info on these. The author hasn't released any code as far as I can see?

The output chip (60pin) looks like a shifter/colour look table and 5bit RGB digital outputs to the resistor ladder.