1.1 GeneralThis International Standard is applicable to NPP computer-system hardware for systems of Class 1 and 2 (as defined by IEC 61513).The structure of this standard has not changed significantly from the original 1989 issue;however, some issues are now covered by standards which have been issued in the interim(for example, IEC 61513 for system architecture design) and references to new standards have been provided where applicable. The text of the standard has also been modified to reflect developments in computer system hardware design, the use of pre-developed (for example, COTS) hardware and changes in terminology.Computer hardware facilities used