I owned an Atari 800 computer. It had 48k memory and software was on cartridges. You could buy (which I did) external cassette tape and 5 1/4″ diskette drives. I got an Atari 300 baud modem and connected to CompuServe in 1984. The communications software was on a cartridge.
I had an Epson 9-bit dot matrix printer which connected to the Atari through an interface box called an Ape-Face.