for S12 family there is mentioned core clock and bus clock, which is half the core clock.
now each instruction cycle is one bus clock or core clock ?
If you haven't already seen it, then take a look at the S12XCPU datasheet. That lists each instruction and its cycle count.
Looks like S12XCPUV1.pdf is still the current version.
the correct version of the CPU reference manual depends on the actual MCU family used:
* most S12 devices generally refer to the S12CPUV2 Reference Manual (S12CPUV2.pdf, latest Rev as of today: 4.0)
* some S12X (e.g. S12XD) refer to the S12XCPUV1 Reference Manual (S12XCPUV1.pdf, latest Rev as of today: 1.01)
* most S12X (e.g. S12XS, S12XF, S12XE) and recent S12 devices (e.g. S12P) refer to the CPU12/CPU12X Reference Manual (S12XCPUV2.pdf, latest Rev as of today:1.03)
This last document mentioned above actually describes the all existing ISA versions for CPU12 and CPU12X.