Shift registers are one of the main blocks in processors. In this paper, two new universal shift registers are designed based on Quantum-Dot Cellular Automata (QCA) nanotechnology. Both of the proposed level triggered and edge triggered universal shift register in QCA technology shows good performance in regards of the number of cells, occupied area, delay, and power. These designs also have reset abilities. Simulations show that the proposed 4-bit level triggered universal shift register with reset ability has 1057 QCA cells, 1.27 μm2 occupied area, and delay of about three cycles of QCA clock. In addition, the proposed rising edge triggered 4-bit universal shift register with reset ability has 1085 QCA cells, 1.27 μm2 occupied area, and delay of about three cycles of QCA clocks.
