Cortical Stacks are perhaps the most complicated, yet most spread technology ever designed and deployed throughout Known Space and were developed in the waning corporate age in the late 22nd century.
About 10 mm in diameter and with a length of 50 mm, these devices are capable of hosting and running an entire sophont mind state.
Implanted into a sophont’s brain at birth, these devices have made a permanent death a thing of the past, with individuals able to sleeve into a new body, be it biological or technological in nature, after their initial bio death, or even earlier, if they so chose.
(See the Altered Carbon universe for more information)
The encrypted nature of Cortical Stacks has made any attempts to find a way to edit their contents impossible, though rumours of Editor devices persist to this day, centuries after their initial creation.
Forking the content of a Cortical Stack is a part of the creation of Indentured Servants.