Calendar conversion for real-time systems

In some applications of real-time systems such as monitoring and control, calendar referencing plays a significant role. The system needs the precise year, month, day, hour, minute and second in order to function correctly. Generally, real-time systems are based on computers whose operating systems use the Gregorian calendar. The official calendar of some countries, however, is not based on the Gregorian calendar. To reduce the human errors and make the system friendlier, it is necessary to present the date in the local format. In this paper, the optimum method of time-keeping for a distributed real-time system is described and then a solar calendar called Khayyami is reviewed and a novel algorithm for conversion between Gregorian and Khayyami calendars is presented. Khayyami is the official calendar of Iran and Afghanistan and is used in surrounding areas such as the Central Asian countries and Kurdish area. The methods described in this paper were implemented in a monitoring and control system and the practical results justify these. (C) 2004 Elsevier Ltd. All rights reserved.