Restomodding a 1995 GPS Time Server with a Raspberry Pi
Rebuilding a 1995 GPS Time Server so I don't get Telstra'd
Jeff Geerling resurrects a 1995 TrueTime XL-AK GPS time server by installing a Raspberry Pi 5 and a GNSS HAT inside its vintage chassis. He configures it as a stratum 1 NTP server using Chrony, with tweaks like isolating PPS interrupts on a dedicated CPU core and thermal management for stable timing. The project also includes driving the original 16x2 LCD and bicolor LED, plus adding retro services like Time and Daytime protocols and AppleTalk for vintage Macs. All code and designs are open source.
Airflow, especially that from HVAC systems, makes the Pi's oscillator go wild—stable clocks like consistent drift, because it's measurable.