There is disclosed herein an improved card reader for a security system utilizing a central controller and a plurality of card readers for controlling traffic through critical doors in a facility. The improved reader includes means for improving the system throughput by buffer storing large numbers of transactions all occurring within a short time for time clock functions in time and attendance applications for hourly employees. Also disclosed are means for conditioned emergency responses to sensed changes in status of alarm contacts coupled to the reader and located in the vicinity of the reader within 2 miles. There is also disclosed means for temporarily storing transaction information for transactions made during periods when communications with the controller are lost. During such degraded mode operation, access is granted to cardholders with the proper system code and their ID code and the time of the transaction are stored in a buffer. When communications are restored, the transactions saved in the buffer are sent to the controller.