CAP computer

[1] The sign currently on the front of the machine reads: The CAP project on memory protection ran from 1970 to 1977.

The CAP was designed such that any access to a memory segment or hardware required that the current process held the necessary capabilities.

Instead of the programmer-visible registers used in Chicago and Plessey System 250 designs, the CAP would load internal registers silently when a program defined a capability.

This removed the need for separate modes of operation, as each process could directly access the resources of its children.

[4] In 1981 the MACRO SPITBOL version of the SNOBOL4 programming language was implemented on the CAP by Nicholas J. L.

The CAP Computer as it currently stands in the Cambridge computer lab.
Archive photo from 1979, showing the inside of the machine and its connection to the Cambridge Ring .