Some examples of "nonflexibly-attached expansions" I can think of, though not arbitrarily expandable like the TI-99/4A: * Sega Genesis (CD, 32X, Modem, Sonic &

Some examples of "nonflexibly-attached expansions" I can think of, though not arbitrarily expandable like the TI-99/4A: * Sega Genesis (CD, 32X, Modem, Sonic & Knuckles, Game Genie, Power Base Converter -- most of which could be attached at once [1], and a few games even required both the CD and 32X) * Nintendo GameCube (the Game Boy Player attached to the bottom) [2] * Epson HX-20 laptop (various expansion units could attach to the side, though only one at a time) [3] [1] https://www.youtube.com/watch?v=Y55ZBT_UcmU https://www.youtube.com/watch?v=Y55ZBT_UcmU [2] https://upload.wikimedia.org/wikipedia/commons/5/50/GameCube-Game-Boy-Player.jpg https://upload.wikimedia.org/wikipedia/commons/5/50/GameCube... [3] http://www.decodesystems.com/epson-hx20.jpg http://www.decodesystems.com/epson-hx20.jpg