A new thin-film metal-insulator-metal device is described. After the insulator has undergone a forming process, which consists of the electrolytic introduction of gold ions from one of the electrodes, its conductivity is observed to have increased quite markedly. In addition the sample displays negative-resistance and memory phenomena. It is shown that under the appropriate switching conditions the device can be used as a non-volatile analogue memory with non-destructive read-out. The theory of operation of the device is also presented.