4-bit-Parallel-real-time-clock-modules-RTC-7x-series-Epson-Toyocom-Q42724211000200-Real-Time-Clock-Module-YY-MM-DD-Date-Format-HH-MM-SS-Time-Format-Parallel-Interface-RTC-Features-Battery-Backup-Power-1 M Hz-Clock-Frequency-50ppm-Frequency-Precision-4-5V-to-5-5V-Supply-Voltage-10-C-to-70-C-18-DIP-Case-The-Epson-Toyocom-RTC-72421B-&-RTC-72423B-Modules-are-4-bit-Parallel-Interface-Real-Time-Clocks-that-can-be-Connected-Directly-to-a-Microprocessor-Bus-These-Devices-Feature-a-Bui