Which of the following memories must be refreshed many times per second?Select one:a.PROMb.RAMc.DRAMd.SRAM

The correct answer is c. DRAM. Dynamic Random Access Memory (DRAM) needs to be refreshed many times per second because it stores each bit of data in a separate capacitor within an integrated circuit. The capacitor can either be charged or discharged; these two states are taken to represent the two values of a bit, conventionally called 0 and 1. The electric charge slowly leaks away, so without intervention the data on the chip would soon be lost. To prevent this, DRAM requires an external memory refresh circuit which periodically rewrites the data in the capacitors, restoring them to their original charge. This refresh process is the defining characteristic of dynamic random-access memory, in contrast to static random-access memory (SRAM) which does not require data to be refreshed.