Monday, May 28, 2001		Bits & Bytes

Ferrite core: A form of core memory for data storage. The core is made of tiny ferrite rings threaded with wires that are magnetized by electrical current. The two possible polarities of magnetization were used to represent the binary values zero and one. Data are stored by magnetizing an array of cores in a particular combination of zeros and ones. Data are retrieved by sending electrical pulses to the specific array of cores holding the desired information. The pulses reverse the direction of magnetization in the cores, including output signals corresponding to the stored data.

Core memory: The old term for main memory, which was composed of doughnut-shaped magnets called cores.

Main memory: Refers to physical memory that is internal to the computer. The word main is used to distinguish it from external mass storage devices such as disk drives. Another term for main memory is RAM.

FECN: Short for forward explicit congestion notification, a Frame Relay message that notifies the receiving device that there is congestion in the network. A FECN bit is sent in the same direction in which the frame was travelling, toward its destination.