Dennard combines a transistor
with a capacitor in a revolutionary memory cell. RAM, a random Access Memory, the
short-term, high-speed ‘working’ memory of a computer, has existed since the
invention of magnetic core memory in 1949.
Modern RAM, though, owes its invention to Texan Robert Dennard (b.
1932).
In 1966, Dennard was working at
IBM’s Thomas Watson Research Centre. IBM
knew that magnetic core memory was too blocky, power-hungry and slow, and that
transistors would be the answer to replacing it. They had reduced the problem of storing a single
bit of memory to a cell that used to only six transistors. Added to a silicon chip, this cell was
already tine compared to a magnetic core.
Dennard, though simplified the memory cell even more to a single
transistor and a capacitor, a component that can hold an electric charge. The memory was used to read and write it. Capacitors “leak” charge through so the
memory had to be continuously refreshed, many times a second. Because of this constant forgetting and
refreshing, Dennard’s system is called “Dynamic” RAM or DRAM.
Despite its need to be refreshed,
DRAM had a world-beating advantage. With
only two components, which could be placed side in the thousands on a single
silicon chip, it was the smallest memory ever made. The computer industry quickly took advantage
of Dennard’s invention and fledging company Intel relased the first commercial
DRAM chip in 1970. Magnetic Core memory
became the technology of yesteryear almost as soon as Intel began to ship its
new chip.
