The Ship Computer is a storage block found exclusively in Crashed Spaceships.
These blocks can only be found in Crashed Spaceships.
When initially found in Crashed Spaceships, these blocks can be scanned (right clicked) with a Sonic Screwdriver to unlock either the Mk3 (Classic) or Mk7 (Modern) Police Box Exterior.
The computer will no longer be able to provide Exterior schematics if it has been scanned with a Sonic Screwdriver.
You can only obtain one schematic per Ship Computer.