English: A magnetic-core memory module from a PDP-5 computer. The module is designed to plug into the backplane of the computer, held in place by two large T-handle jackscrews, each about 1 foot (30 cm) long. This particular module was made by Electronic Memories Inc. and accepted by Digital Equipment Corp. on 9/23/1964. The individual cores inside this memory are 0.05 inches (1.27 mm) in diameter, and the memory cycle time (read plus refresh) was 4 to 6 microseconds.