[TUHS] Do you have any historical UNIX computers?

H.J.Thomassen hjt at xs4all.nl
Thu Jun 12 06:21:41 AEST 2025


I still have two 19" racks with the main components of the PDP-11/45, 
built in 1972, on which we started using UNIX 5th Edition in late summer 
1974. Later it ran 6th and 7th Ed. CPU with front panel w. switches and 
lamps, RK03 cartridge disk (2.5Mb!), floating point processor board 
(serial number 1), several core memory banks among which 8K ones, 
DEC-tape, ASR33-TTY, dozens of mini-lightbulbs, not a single LED. Its 
hour-meter has clocked 122532: that's 13,97 years.
It is complete but doesn't run. I remember from the days when I 
administered it during its productive life that it required .5 day of 
maintenance per six weeks, by a qualified service engineer: tuning power 
supplies, adjusting the disk head with the help of a special "alignment" 
disk cartridge, checking the fans (25+ in just those two racks), etc. etc.
The CPU consists of 17 large PCBs. The combined MTBF of these PCBs was 
1.5 years approx. Then the service engineer came with his box with 
exchange boards and swapped until the machine was up&running again. 
Without a maintenance contract such a board had a 5-figure exchange fee.....

Hendrik-Jan Thomassen



More information about the TUHS mailing list