Design principles of the magnetic tape system for the atlas computer

Atlas is a high speed computer typically performing a floating point addition in 1.4 ¿s. It has been designed to accommodate information transfers from eight tape channels simultaneously, information either passing into or out of the computer. Under these circumstances the computer has to deal with a transfer rate of 7.2 × 105 6-bit characters per second. A switching system interconnecting tape decks and channels permits more than eight tape decks to be provided on an Atlas computer. After a brief survey of the Atlas computer the paper discusses tolerances on the packing density of the tape system, the layout of information on tape and the virtues of a fixed block length on tape. The program and automatic circuit techniques for dealing with the tape store are described briefly, and the system of checking tape transfers is outlined.