A device according to examples of the present disclosure includes a crossbar array including a cell. The cell includes a first resistance switch and a second resistance switch connected in series with the first resistance switch. The first and second resistance switches have different switching characteristics. One of the first and second resistance switches may act as a switch, while the other of the first and second resistance switches may weight the switching behavior of the one that acts as the switch.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A device comprising: a crossbar array comprising a cell, the cell comprising: a first resistance switch; and a second resistance switch connected in series with the first resistance switch; wherein the first and second resistance switches have different switching characteristics. 2. The device of claim 1 wherein: the first resistance switch comprises a first memristor connected in parallel with a resistor; and the second resistance switch comprises a second memristor. 3. The device of claim 2 wherein the first and second memristors are the same. 4. The device of claim 2 wherein: the resistor is a first resistor; and the second resistance switch comprises a second resistor connected in parallel with the second memristor. 5. The device of claim 1 wherein: the first resistance switch comprises a first memristor; the second resistance switch comprises a second memristor; and the first and second memristors are different. 6. The device of claim 1 wherein: one of the first resistance switch and the second resistance switch acts as a switch; and the other of the first resistance switch and the second resistance switch weights the switching behavior of the one. 7. A method to perform spike-timing-based recalls, comprising: applying a multi-spike train to an electronic synapse between an electronic input neuron and an electronic output neuron to switch a temporal weight of the electronic synapse but not a spatial weight of the electronic synapse, wherein the electronic synapse comprises a cell with a first resistance switch and a second resistance switch connected in series and having different switching characteristics, the temporal weight comprises the first resistance switch, and the spatial weight comprises the second resistance switch. 8. The method of claim 7, wherein the multi-spike train comprises set pulses from the electronic input neuron followed by reset pulses from the electronic output neuron, the set pulses are greater in number than the reset pulses, the set pulses turn on the first resistance switch and therefore the electronic synapse without affecting the second resistance switch, and the reset pulses turn off the first resistance switch and therefore the electronic synapse without affecting the second resistance switch. 9. The method of claim 7, wherein the multi-spike train comprises alternating set and reset pulses from the electronic input and the electronic output neurons, respectively, to repeatedly switch the first resistance switch and therefore the electronic synapse on and off without affecting the second resistance switch. 10. The method of claim 7, wherein the multi-spike train comprises reset pulses from the electronic output neuron followed by set pulses from the electronic input neuron, the reset pulses are greater in number than the set pulses, the reset pulses turn off the first resistance switch and therefore the electronic synapse without affecting the second resistance switch, the set pulses turn on the first resistance switch and therefore the electronic synapse without affecting the second resistance switch with the set pulses. 11. The method of claim 7, wherein the set and the reset pulses are square pulses. 12. The method of claim 7, wherein the spatial weight comprising the second resistance switch determines a total charge through the electronic synapse. 13. A device comprising: a first switch comprising a first memristor connected in parallel with a resistor; and a second switch comprising a second memristor; wherein the first switch is connected in series with the second switch. 14. The device of claim 13 wherein the first and second switches have different switching voltages.