Also called a neuron star, this is an archailect based upon a computational substrate comparable in mass, size, and density to a neutron star, about 4X1030 kilograms (2 solar masses).
The computronium is believed to consist of highly dense materials such as exotic forms of neutronium known as 'nuclear pasta', and possibly magmatter and quarkonium that are not within the capabilities of modosophont-level technology.
Such complexity is often considered to be the bare minimum housing for an archailect at the full S5 rating.
Text by Damien Broderick, in Anders Sandberg's Transhuman Terminology additional material by Adam Getchell and Steve Bowers Initially published on 09 December 2001.