Longines nixie tube Chronometer from the late sixties

[J Thomas]

[Old Tom]

More probably TTL- RTL just didn't have the medium complexity necessary to build a clock (in a case that size!). If I remember correctly Texas Instruments introduced 54 & 74 series TTL at the end of 1966 and in the first tranche of chips were counters and nixie drivers suitable for building digital clocks. Instructions for this clock show a power consumption of about 18 watts which is about right for a standard TTL clock with nixies.