The Atari 800's expansion options were limited. Atari avoided an Apple II-style internal card bus, instead relying on an external serial port for peripheral expansion; access to this port was through a 13-pin connector on the side of the unit.
A limited number of peripherals (including disk drives, printers, and modems) could be daisychained together through this port. Though this serial-based expansion method was reasonably user-friendly, it suffered from slow speeds and large tangles of cords.
Republished with permission from PC World (view original version)