You use a 27512 chip, move the jumper over on the weebly, and put the images in these places on the 512:

U1=1000-17FF
U5=1800-1FFF
U2=5000-57FF
U6=5800-5FFF
U6=F800-FFFF (2 copies, technically you only need the top 8 bytes at FFF8-FFFF)

The rest of the 512 doesn't matter. Note that they are not put in the 512 image "in order" - it's u1-u5-u2-u6 order

Oh and what custom variants are they?

Both those mods were made by me.

There is another stargazer one (available on IPDB, oliver kaegi) that disables the spot the constellation and kneecaps the bonus multiplier when it's over 4x, sets it back to 1x on the next ball.

The other stargazer is the "Raymond Davidson" suggest mods (from slam tilt podcast) where he suggested shoot left or right drop banks to light corresponding spinner, complete center bank to light star rollovers for ONE award. The bonus multiplier steps back 1/2 each ball (rounding up, 5x would become 3x the next ball) to try and sit on the bonus multiplier.

Sorry I only have enough eproms for my own use, you can get a cheap rom burner for about $35 (minipro) and eeprom versions of the 512 (about $1 ea.). Andrew barakandl might be able to burn you roms, some of the variants are on his combo rom already. The stargazer one he def. has and I think it's already on there. I don't use the combo rom itself much for my own use since I'm always swapping roms and versions in and out of my games for testing.

Yes I think the star gazer one is on there you can double check with him. He usually adds the alternate versions.

It's a little black rectangle on two pins in most revisions it's near the 512 socket.

Only for the arduino board.

The weebly board offers more ram/rom space in the native (6800) format.... write games just like they did back in the day! No fancy IDE.

There was a version that modifies the way stuff gets spotted, but nothing like a complete rewrite.

I forget why the arduino doesn't work on the weebly, and if there's a workaround. I know one of the signals isn't present on j5, but there might be another reason why it doesn't work.

Why would you need to do that? The arduino doesn't use the original software in any way. Or the 6800 processor, it halts it.

Somewhere in one of the arduino threads barakandl points out what's missing/needed to have it work on his board.

I have a large stack of original boards so never been a worry for me. I have a large stack of weebly boards as well, for the previously mentioned 6800 native coding.

https://pinside.com/pinball/forum/topic/silverball-mania-2021-new-code-for-bally-sbm-1980#post-6565198

Depends on the expansion board and how homebrew it is I guess. Some people build those on perfboard.

I pretty much just put one version of software in a machine no need to switch back and forth. If I want options, I'll add options on the dip switches to turn things on and off.

What I'd REALLY like to use the arduino setup for is a debugging setup for the normal software. Don't know enough about the hardware 6800 signals to implement that..... so you can interrupt the 6800 regular running program, with its memory and registers intact, and inspect it. Likely not possible though, since the registers are internal to the processor, and you'd need some way to pass them back and forth.