3 Ways to Keep Older Roombas Out of Trouble

Use virtual wall units Most older models (500, 600, and 700 series) came with small hockey puck devices that emit an invisible IR beam. Place one in a doorway or across a threshold, and the Roomba will not cross it. Replacement units are cheap on eBay.

Try magnetic tape Some Roombas (600 and 700 series) respond to a strong magnetic strip laid on the floor. Tape it down, and the Roomba treats it like a cliff. It is janky but effective.

Close the door or block the path If you have no accessories, just close the door or block the area with a box. It is not elegant, but it is free.