The Hewlett-Packard 59309A is an HP-IB digital clock.
This is a really nice little clock made entirely from TTL and CMOS ICs. It supports an external time reference input (1MHz, 5MHz, or 10MHz, selectable by a switch on the A2 board) and has an HP-IB interface. The time and date can be set either from the controls hidden under the front panel or via HP-IB commands.
