smbakeryt built his own Hayes Chronograph:
I’ve always wanted a Hayes Chronograph, but have never been able to acquire one, so I finally broke down and just made my own. The Hayes Chronograph was a compliment to Hayes line of smart modems, and implemented a real time clock for computers that didn’t have a built-in clock. They were popular in the early 1980s, and became less popular as computers began to either come with clocks built in, or add-on boards with clocks became popular. My “remake” keeps the theme of having a Vacuum Fluorescent Display (VFD), but switches to a GPS as a source of time synchronization. A raspberry pi is used as control — this thing could be used as an NTP server!. My design retains the DB25 for communication with the host computer, and attempts to replicate the original Hayes protocol.
See the full post at smbaker.com.