dongle-disk = D = doorstop

donuts n.

[obs.] A collective noun for any set of memory bits. This usage is extremely archaic and may no longer be live jargon; it dates from the days of ferrite-core memories in which each bit was implemented by a doughnut-shaped magnetic flip-flop.

--The Jargon File version 4.3.1, ed. ESR, this entry manually entered by rootbeer277.