> is this actually useful without a cartridge slot?
It has 2 of them actually. One standard one on the back and an internal one that I think doesn't use the standard connector that is intended for hardware expansion. Despite what the product page says, the internal slot is mapped to slot 2 and not slot 1 in the MSX mapping system, so it doesn't conflict with the external cartridge slot.
That said, most computers of this era including the MSX had a fair bit of software released on cassette tape as well. There were also disk drives and software released on disk as well.
Looking at some of the more famous games for the system: Metal Gear was released on cartridge, but Snatcher was released on floppy disk with an expansion cartridge that contained extra RAM and a sound chip. It seems this system has support for that expansion builtin though.
It has slots. But anyway you do bot need slots at all. MSX was mostly tapes at that time. I’m sure there is either a simulator, or you can generate the sound from binary files.
I thought that the MSX kind of depended on cartridges.