They aren’t yet competition for Intel, but bioengineers have created a one-bit “memory” made of DNA that can record, erase and rewrite data within living cells.

One day, doctors might be able to insert such devices into a cancer patient to tally how many times a cell divides and flag when to shut the cancer down. Or researchers might track exactly what happens inside cells as they age.

The work is a step forward in synthetic biology, a new field in which scientists create tools to control life’s basics from the cell on up.

“We can write and erase DNA in a living cell,” says Jerome Bonnet, a bioengineer at Stanford University. “Now we can bring logic and computation inside a cell itself.”

Bonnet and his colleagues, led by Stanford’s Drew Endy, describe the feat in a paper published online May 21 in the Proceedings of the National Academy of Sciences.

Scientists have long dreamed of putting