A memory controller (40) is adaptable to scaling of a system clock frequency, to enable another device (10) to access a memory (20), and has a part for outputting control signals having some timing characteristics not entirely scalable with scaling of the system clock frequency. In response to an indication of a change in a frequency of the system clock, the memory controller adapts the part autonomously to enable it to output new digital memory control signals synchronized to the changed system clock and which also have the non scalable timing characteristics. This avoids the need for the processor to adapt the memory controller. Hence the adaptation can be carried out more quickly, leading to less disruption to other parts of the system and means the frequency scaling can be carried out more often.