Can't say for sure but will probably work. If the nano will drive A12 on the MPU through J5 then two jumpers need changed if they exist (MPU newer than a couple years old) otherwise there could be contention with a 74hct32. Above J5 two solder pad jumpers 'J-(A8-A12)' removed and 'J-A12 added. That puts J5's A12 pin right on the CPU address bus. If those jumpers do not exist then its already connected with A12 to J5 and no modification needed.

Plugging a leaded wire into the CPU socket for the IRQ may damage the IC socket used if you ever want to go back to the normal processor. Attaching a wire to a socket mating header pin or perhaps a cut off chip leg may be better. Use at your own risk on the nvram.weebly replacement.

I have an Alltek board, has anyone tried this with one?

I do, but I have ZIF sockets on all my games that I do this on.

It wouldn't be that hard to build the daughter board that people use to hold pincoder 's test roms and adapt that to something else, as well.

Since you already have the arduino plugged into J5 with all the correct address and data lines there, maybe have it act as an eprom emulator. No reason why it couldn't.

You could instead somehow hook up to the /IRQ line at the top leg of the pull-up resistor R134 down the bottom of the factory MPU boards.
Note the Stern MPU-200 boards actually have the CPU /IRQ line routed to J5 pin 34. It might not be too much of a stretch for people going through this to extend their existing J5 pin header and add the CPUs /IRQ line there.

This is extremely cool!!! Stars was already a really neat game, I’m sure this makes it even better.

Top of R134

Indeed it should be: Is VMA going to be a problem with the Arduino driving it? There's a 3.3k ohm resistor in series with the VMA signal out of the 6800 so it can be driven externally.

6800_Halt.png

What would be really cool is if you could put it in the menu system somehow so you can change easily between them. 0 for Normal rules and 1 for Updated rules but I am sure that isn’t an option or it would have already been done.

If a12 is grounded through the j5 connector then the 'j-(a8-a15)' jumper out and 'j-a12' in in case the 74HCT32 output used to keep the sb300/SB100 out of the expanded nvram space has contention trying to drive the forced to ground a12 on the nvram.weebly replacement. Might damage the chip.

Very nice. Well-written code as well (not 10 layers of esoteric classes, macros, obscure library calls, and variable names containing only one letter from the alphabet as is often seen on github).

I'm not sure how the Arduino thing works... but the usual course is at boot time it looks for an input or interrupt. Like say you power the game on with the red test button or Credit button pressed.... if that happens it runs stock code.... if not it runs modified game rules code. something like that. Or pressing the red test button gets you into a menu system where you can change the rules. That's how Pascal does it with his Gottlieb system80 board. Basically at power on you hold a button (Credit button or red test button, i forget), and you can set the game to run any of the games he has programmed into his Arduino based board.

DickHamill Im happy to report I have my Stars running with your rules, but with the older stars2020.ino without SelfTestAndAudit.h. Running the lasted code and powering on wasn't locking on coils like i first thought, it was testing all the coils and switches at once. Pressing the coin door audit button would cycle, but I couldn't get it to start a game. I put the M6800 back in to test and all was normal. For now I'll just run the older code and enjoy some pinball. Thanks for the help.

This is incredible. Very nice work!

@dickhamill, I just uploaded the newest code. I love it! The new skill shot rules are awesome. The match feature is really well implemented. I never expected to be so impressed by a match screen. I figure a code update after 42 years deserved a little flair. The 8x32 matrix display is run from a different arduino and blue tacked to the backglass for the time being. My backglass is pretty roached, so once I figure a permanent location I'll have no issue scraping the paint so that it's visible from behind. Trigger warning: LEDs in an early solid state Stern. I had to butcher the video file to upload a gif with Pinside's 10.5 mb limit.

stars20208x32 (4) (resized).png

D'oh! Never mind, the gif doesn't move.

Not even close. I like that the stars goal is actually attainable in a 3 ball game. I've done that and the pop bumper one, but the target goal will probably take a while. wizard modes aren't supposed to be easy any way.

I bet this new code increases the demand for the game. Stars had lagged a bit behind some of the other classic sterns, and not because it’s layout. I can’t wait to get to play this new code at a show somewhere.

I am not sure why it has lagged. Honestly one of the better Sterns!
Maybe due to sheer # made? With over 5000 of them and seems like they were consistently liked/did well on route, that many survived... probably has helped keep price down?

Glad I got mine I doubt it will ever leave. Wish there was a bundled packaged that could be purchased trying to source all this stuff from Canada sucks lol.

I always thought Stars was one of the better if not best Stern MPU100 game.

Yes, the solution is brilliant. Our machine is on location and the ability to switch is ideal as we have regular and competitive play. Once I get all of the parts sourced I should be able to do a stream on it too show it off as we have full stream capability at our location. Do you have a link to source the switch from? I am going to build three of these as a friend has a Stars, and another friend as Blackjack .

Have the arduino control the switch. It boots up and then if you want the old code, it switches the switch and stops whatever its doing to the mpu board. If the Halt line is the only one that needs to be switched on and off, a simple transistor circuit should be able to do this to not overload whatever the sink capability of the arduino pins are. If it's more than one line, I'm sure there's lots of IC's that can do the job with one signal from the arduino.

I think you already mentioned it but is there any Arduino ROM space left to implement the stock ruleset?
If not, is it possible to extend the Arduino ROM space by using a reprogrammed EPROM on the MPU board? Probably too much work.

Since uploading a gif was an epic fail, here is a youtube link of a brief demo of the LED matrix:

It's a super simple VERY basic tweak of a sample sketch in the MD_Parola library.

@quench: I think when I uploaded the latest code last night the Nano memory was 89% full. I believe an Arduino mega would have more than enough memory to do anything you could realistically ever want to do. It would also have the advantage of having 3 discrete serial ports besides the usb for programming. That way you could have your laptop plugged in for debug while also sending data to a wav trigger for audio, data to the LED matrix, and have a spare channel for something else. I would imagine with the OS already written, if the classic rules were coded along with some sort of menu/ choice of game to play a button could be added to the inside of the coin door to switch. Video above as an example of 2020, or Classic for the old rules. I realize I'm leaving the scope of the original plan to only use stock hardware, but I think it would be amazing. I know next to nothing of coding but I have all of the hardware, a soldering iron, and the will to be the guinea pig if some of you Pinsiders that are smarter than I am can tell me what I need to do.

I'd like to take a second to thank DickHamill for lighting a fire under a few of us and putting in a lot of hard work to figure this out and share it with us so that we can do it as well. The man didn't even dump the roms. He hooked up a freaking oscilloscope and figured out how it worked and wrote code to an Arduino to make it even better. He then gave detailed instructions that even a monkey with a soldering iron like me could figure out. You rock! If you don't change a thing, it's already amazing!

cfh thanks for the non-Amazon links. Amazon sucks. I got a the nanos from a guy in Texas so they'd get here a little quicker than the ones from overseas. Looking forward to the project! Got a couple spares as well.

I don't know how much memory the Arduino has, but Pascal re-wrote about 20 gottlieb system80 games in his Arduino based CPU board. you just select the game you want from a menu. Me think this may be possible for this unit too...

if it was me, i would use the exact same 'core' for any game. Changing between games should be simple and occupy small space...

and Chalkey, i'm with ya. i don't shop on Amazon. it makes me feel dirty.

CousinPookie, may I just say that backglass you got going on there has got to be the greatest thing in pinball I’ve ever seen. I want that BAD but I’m the one monkey with a soldering iron that can’t do it. How much would you want to do mine? I’ll send you whatever you need from my game.

We are

@xtraball: There's no solder in that circuit. Below are the parts that I used. All you need besides that is some wire to power it all up. It's really not that complicated. As a complete Arduino noob, I figured it out in an evening. I only changed a few things in an example sketch to make it work.

If you get the parts I'll help you get it going. Note that it's just blue tacked to the front of the backglass.
Arduino starter kit: https://www.microcenter.com/product/617246/inland-nano-ft232-starter-kit
Dot Matrix LED: https://www.amazon.com/gp/product/B07FFV537V/ref=ppx_yo_dt_b_asin_title_o09_s00

You have 3546 of free program bytes.
Stars stock code is about 4k bytes. Based on experience with other early games, half or more of that will be the operating system.

You've already written your operating system. I know you can't compare code bases 1 to 1 but is it conceivable someone could add the simple stock ruleset onto your operating system with the spare space available?

Wow, nice touch!

I have those spring loaded clips on my logic probe, half the time I connect them to these old MPU boards they don't make good contact. Add that resistor R134 is usually in the strike zone of battery corrosion so its legs will more than likely be rather tarnished. An alligator clip might work better but truthfully, I agree that it's not a good solution.
Personally I would install 2 header pins on the board (next to J5) and wire the /IRQ line to pin 34 like the MPU-200 boards. I don't know how comfortable you or others will be with doing this.
It's a bit of a tricky one..

Were you able to determine which switch to use? We have all of our stuff in our cart ready to go.

Thanks!!!

Love Stars? Show your love with a SK-1 spaceship lapel pin!

https://pinside.com/pinball/market/shops/1255-tommy-s-pins/03758-stern-electronics-collector-lapel-pins-outer-space-series

Awesome news we are building 5 of them just more economical that way, and we bought both kinds of switches just in case look forward to getting all the parts and trying it out!!!