Home Page Forums MAME MAME Cart slot with ROM and NVRAM options

I'm currently working on a driver for the Casio CZ-1. I'd like to implement a cartridge slot that can support both:

• Swappable 16kb and 4kb NVRAM carts (e.g. the existing casio_ra3_device which uses device_memcard_image_interface)
• Arbitrary-sized ROM carts with a software list

I'm only really familiar with slots where either all of the options are ROM/softlist based, or ones where all of the options are peripherals. Is there a particular ideal way to do this? Better yet, any particular systems that are a good example?

Maybe you can find some inspiration in the TI-99/4A cartridge emulation from me (src/devices/bus/ti99/gromport/cartridges.{h,cpp}).

The Virtual Boy cartridge slot (src/devices/bus/vboy) is pretty simple – it supports cartridges with onboard NVRAM as well as ROM.

To clarify a bit, I'm aiming to support carts with either NVRAM or ROM, not both - i.e. the ROM carts are just read-only versions of memory cards with factory presets, etc. Ideally the NVRAM ones should still allow creating a new image through the UI. I thought about just using my existing device_memcard_image_interface subclass and letting it behave as read-only when loaded from a software list, but I'm not sure if that makes sense / is the best approach.

I think what Vas suggested is fine. Image devices have an is_creatable() function that just needs to return false for the ROM cards and true otherwise.

By quick glance (and assuming I'm getting everything right from the schematics) the carts are 30-pin, single row, 8-bit of data bus and up to A13, Chip Enable, R/W and a couple extra pins I can't read properly due of poor scan (a "VBR" that goes to "VBU" connection, and a "KIO").
imho you can perfectly self contain the cart mapping to 0x0000-0x3fff from your bus a la vboy, where slot options can access that only and the couple pins really required for emulation.

The only complication is if it needs to be able to deal with on-the-fly card changes. If it has to deal with that, you can’t really do it with the slot/card paradigm because that forces you to do a hard reset for card changes. If that’s the case, you need to do it was a device_image_interface with custom implementation for software list load/unload.

Yeah, it should be hot-swappable like the existing casio_ra3_device (which is one of the supported cart types here, alongside the larger RA-6 RAM cart and simple ROM carts). So would it make sense to just add read-only software list support to the existing NVRAM image device?

Yeah, you can add software list support to the existing device.

I'll do that then, thanks.