The phantom clock refers to the feature of using the same interface to read and write to the clock registers, and to write to the memory. To avoid conflict with reading and writing to SRAM memory, communication with the phantom clock is established by pattern recognition on a serial bit stream of 8 bytes. For example, the pattern for DS1244 is C5, 3A, A3, 5C, C5, 3A, A3, and 5C. The phantom clock is enabled and data transfer to or from the timekeeping registers can proceed after the pattern is sent to DS1244.