 One of these slots is populated with an ISA card, which provides connections for sound at the rear of the machine and a connection for the Mega Drive cartridge at the front.The other slot was left free for expansion (such as the addition of a modem or Network Interface Card).The Sega TeraDrive includes stereo RCA jacks and composite NTSC video output for connection to a TV, whereas the Mega PC lacks this feature, but could be connected to a PAL TV through SCART.