CPU 1212C DC/DC/DC without Memory card

I have a CPU as stated above and I have done some program, downloaded and tested then power off the CPU. The next day when i turn it on again, I realized all the DB blocks data become 0. But I believe that my program is still loaded inside the PLC, after i setting all the setpoint back to the DB blocks, the PLC is functioning again. Is this normal? Why can the program stored inside the CPU but not the DB data?

I'm using TIA Portal V11 SP2

Thanks.