Correct.
It was a PC. Albeit, a very small one.
It has an intel CPU, a tiny flash disk which would prob hold the OS and a few other things hidden under the black plastic cover.
There is also an Eeprom which I suspect holds the ROM and snaps?
The suppliers would be getting them from the factory, you tell them what games you want and they burn the ROMs onto the Eeprom and send it out because they are available as 4, 9, 39 or 48 in one. I think the Eeprom was 8 or 16mb but I can't remember. Would be fairly simple to delete the Eeprom and install your own roms and snaps.
It also has a VGA out, 3.5mm out for sound, a power supply input the same as your PC.
I have one here and the sound on Bombjack sucks ass. Its one of my fav games too.

If you have the skills, buy a PC and get another 4960 odd games for less money.