Arcade PAUSE button hack

[c0nn0r]

Hey guys, I really miss having a PAUSE button on my arcade games. Of course I was raised on consoles that always had a dedicated PAUSE button that I could use when I had to with an interruption. Of course arcade games were not built with a PAUSE option... Hmm.

I did a bit of digging and found out that many of the CPUs (Motorola, Zilog, etc.) used in arcade boards have what's called a HALT feature, which is basically the same thing as PAUSE.

I wired up a button to this specific pins on the M68k of my Shinobi board and lo-and-behold it works! You can check everything out in this video link:

https://youtu.be/kTQ2KlvlboQ

Have any of you guys done something similar? Is there an easier way to get PAUSE functionality in arcade boards?

[Worm2]

I like this! Would be great for some of the longer games. haha

[iankellogg]

most games this will not work. im kind of surprised it even worked there. Most games have a watchdog timer and if you halt the processor the watchdog will reset it.

Some games have a testing mode pause. Pacman comes to mind, which is different than the watchdog.

If you want to do this for every game you will need to disable the watchdog timer somehow when you pause it.  Also if for any reason the game uses dram instead of sram you will crash the game if you halt the cpu.

[offset]

Interesting idea, agreed with Ian on Watchdog, curious though, if watchdog disabled if this would work.

I've been debating a bar top with Tetris for my wife, but a pause feature for her would be awesome so she could pause if the phone rang, etc.

[c0nn0r]

most games this will not work. im kind of surprised it even worked there. Most games have a watchdog timer and if you halt the processor the watchdog will reset it.

Some games have a testing mode pause. Pacman comes to mind, which is different than the watchdog.

If you want to do this for every game you will need to disable the watchdog timer somehow when you pause it.  Also if for any reason the game uses dram instead of sram you will crash the game if you halt the cpu.

Very good info. Thanks for the heads-up on the watchdog timer.

[iankellogg]

I don't think it would work very well in practice. Many games have more than one CPU and those cpu's have their halt's tied back to the main CPU somehow. you wouldn't be able to tie every halt together so you would have to find another way to do it.

[orbit79]

Obviously this isn't a solution across the board, however MVS motherboards have a similar feature mapped to one of the dip switches. So I believe it would be possible to wire up a button to trigger it instead. I haven't done it though. Obviously if you don't have an MVS this info isn't very helpful, but might be for someone.


Sent from my iPhone using Tapatalk

[iankellogg]

There are other games that have descrete pause buttons too.
Pacman/Ms pacman have one for example

[c0nn0r]

Obviously this isn't a solution across the board, however MVS motherboards have a similar feature mapped to one of the dip switches. So I believe it would be possible to wire up a button to trigger it instead. I haven't done it though. Obviously if you don't have an MVS this info isn't very helpful, but might be for someone.


Sent from my iPhone using Tapatalk

Yes. the MVS (as well as Capcom CP Systems) have a DIP switch that is connected to the 68000 HALT pin. This is the inspiration I used to make a pause button for my Shinobi - which does not have a DIP pause switch, but does also use the 68000.

[iankellogg]

neither the CPS nor MVS have a dip switch on the halt pin.

You can't just halt the CPU and have it work. If the game has a working watchdog then the halt pin will crash the processor.

[c0nn0r]

I was able to finally test this on another Motorola 68000 based arcade PCB - this time it's Data East's "Robocop".

As you can see in the video, I'm using the same setup as before, and pause does indeed work as expected without any side-effects.

https://youtu.be/6-x4bYoiIWY