<- Virtual Exhibitions in Informatics

DRAM

In 1966 Robert H. Dennard invented Dynamic Random Access Memory (DRAM) cells, one-transistor memory cells that store each single bit of information as an electrical charge in an electronic circuit. This technology permitted major increases in memory density.

DRAM is a type of random access memory that stores each bit of data in a separate capacitor. The number of electrons stored in the capacitor determines whether the bit is considered 1 or 0. As the capacitor leaks electrons, the information gets lost eventually, unless the charge is refreshed periodically.

Since then capacity was increased  thousands of times and access time was reduced dramatically.

References:
http://www-03.ibm.com/ibm/history/history/year_1966.html
http://de.wikipedia.org/wiki/Dynamisches_RAM