A programmable unit is described. The programmable unit has a memory
device and a read protection device by which it is possible to prevent
data from being read from the memory device. The described programmable
unit is distinguished in that the read protection device prevents data
from being read from the memory device only when a locking tag is set,
and in that the programmable unit sets or does not set the locking tag
automatically as a function of the operating mode that the programmable
unit is in.