目前，美国已售出600套基于计算机的自动化系统。在这600个系统中，大约有400个已上线运行。这些数字不包括大约1000个特殊处理器类型系统，这些系统虽然基于第二代和第三代计算机技术，但不是软件可编程的，因此不包括在与本报告相关的数字中。为了进一步定义本报告的主题领域，它包括安装在建筑物或校园内的系统，用于监测和控制供暖、通风和空调系统，提供维护帮助，发出警报，以及监督火灾和安全警报系统。具体而言，流程工业中为控制和监控流程而开发的系统不在本讨论范围内。 引文:华盛顿州西雅图ASHRAE学报第82卷第2部分研讨会

\At the present time, on the order of 600 computer-based automation systems have been sold in the United States. Of these 600 systems, roughly 400 are on-line and in operation. These figures do not include roughly 1000 special processortype systems which, although based upon second and third generation computer technology, are not software programmable and are therefore not included in the numbers that have relevance in this report. To further define the subject area of this report, it includes those systems that are installed in buildings or on campuses to monitor and control the heating, ventilating and air-conditioning systems, to provide maintenance assistance, to annunciate alarms, and to supervise fire and security alarm systems. Specifically, those systems developed in the process industry to control and monitor processes are excluded from this discussion.