Random-access memory was invented in 1966 when Robert Dennard discovered that a single MOS transistor could control the writing of a charge to a capacitor. This invention created the architecture that would eventually power the world and replace magnetic core memory. The first commercial DRAM integrated circuit, the Intel 1103, was released in October 1970.
Static RAM uses six MOSFETs to store a bit of data and is generally faster but more expensive to produce. Dynamic RAM uses a transistor and capacitor pair to store a bit, which allows for greater storage densities and lower unit costs compared to SRAM. SRAM is often used as cache memory for the CPU while DRAM serves as the main memory in most computers.
Random-access memory is volatile and loses data when power is turned off because it relies on a transistor and capacitor pair to store a bit. The capacitor charge leaks away into the void if not refreshed every few milliseconds. This fragility became the defining characteristic of the digital age where data existed only as long as the machine was alive.
The memory wall is a growing disparity between the speed of the CPU and the response time of memory that creates a bottleneck limiting computer performance. From 1986 to 2000, CPU speed improved at an annual rate of 55% while off-chip memory response time only improved at 10%. This gap is caused by limited communication bandwidth beyond chip boundaries and the enormous increase in the size of memory since the start of the PC revolution in the 1980s.
Robert Dennard, an engineer at IBM, invented the first dynamic random-access memory chip in 1966. His patent filed in 1967 described a single-transistor DRAM memory cell that was revolutionary in its simplicity. The first commercial DRAM integrated circuit, the Intel 1103, was released in October 1970 and contained 1 kilobit of memory.