Our former main reference servers, tick is right and tock is left. On the left side are two simple radio clock receivers. The left one is the Expert mouseCLOCK (by Gude ADS) connected to tick, the right one is the IGEL:clock connected to tock without the adapter (see below).

The PCs shared keyboard and monochrome monitor by the switch box below the monitor. tick was an i486 25 MHz, tock an i486 33 MHz. Both had 8 MB RAM, ISA bus, IDE adapter, 200 MB disk, NE2000 compatible NIC and a XGA graphics card. There was only a 1.4 MB 3.5" floppy disk drive and no CD-ROM drive.

Both boxes were running S.u.S.E. Linux 5.2 with kernel 2.0.33 without graphical user interface. RAM and disk space were fairly sufficient for that. But for Linux installation we had to mount the disks into tack (below) which had 16 MB RAM and a CD-ROM drive. Thereafter the disks were mounted into tick and tock and additional software was installed from the network.

The NTP daemon was still version 3 (xntp3-5.93-export), and we did not change that because the quality of service was quite good. Linux stayed unchanged as well for obvious reasons.

This was a privately owned old PC, bought 1992 and upgraded later: i486 50 MHz, 16 MB RAM, ISA bus, EIDE controller and 1.2 GB disk (1996), double speed CD-ROM drive, 1.4 MB 3.5" floppy disk drive, NE2000 compatible NIC, XGA graphics card, 14" color monitor. It was too weak for MS Office 97.

It was running S.u.S.E. Linux 6.3 with kernel 2.2.13 and optional graphical user interface (slow). NTP daemon was the preinstalled version 4 ntpd.

All three main boards and most of the components were made in 1992, only the cases and some components were newer. Just the newer EIDE hard disk as well as a processor cooling fan failed, but otherwise these "old-tech" PCs have worked for 20 years, the last 14 years thereof on 24/7 duty, without any failure.

These are two low-cost, 'passive' and 'raw' receivers for the German DCF77 radio clock signal. 'Passive' means that there is no power supply. The receiver is attached to a RS232 port and powered by positive DTR and negative RTS line voltage. 'Raw' means that there is no processor. The secondly time signals are received at the RxD line and interpreted by a driver that is part of the NTP software.

This one has been made in 1992 by Gude Analog- und Digitalsysteme GmbH in Cologne, and they still made it 20 years later, just with an USB interface instead of RS232.

This one has been bought as well in 1992, but from IGEL GmbH. Probably they didn't make it but sourced it from Gude. It came with an additional RS232 adapter (middle). Usually, raw DCF77 signals are received at a rate of 50 bps. The adapter transforms the signals to a shorter duration to be received at 1200 bps.