Berlin Uhr

The Berliner Clock that Employs Set Theory
(Photo above taken at 1739 hours, or 5:39PM)

This is the Berlin-Uhr, a clock built to display the time according to the principles of set theory, and is the first of its kind in the world according the the Guiness Book of World Records. The Berlin Senate commissioned Dieter Binninger, the clock's inventor, with its construction and installation along one of Berlin's most glamorous boulevards, the Kurfürstendamm (two images below). Operation began June 18, 1975.

By 1995 the clock was no longer really in servicable condition. Annual maintenance costs exceeded 5000&euro—mostly in the form of replacement lamps—and the senate rejected a line-item budget to keep it going. The clock was moved to its new location at the Europa Center in 1996 (above image), with the center's local merchants collectively as the clock's new sponsor. In its original location the clock displayed the time on both sides, but in 1999 the second side was deactivated, and after rennovation in 2000 it received a face-lift in the form of new glass lenses, a new frame, etc.

The clock can be read by quickly scanning the rows of lights and "summing" the time. The top two rows (red blocks) are for hours, fives and ones, the bottom two rows (yellow blocks) for minutes, fives and ones. To make summing the minutes faster, the quarter-hour increments are colored red. The top, round light blinks every two seconds.

(center image above courtesy of Holger Will, as this appears to be his little widget)

The Table-top Model

A table-top model of the Berlin-Uhr was manufactured between 1980 and the mid-nineties or so, and has at its core the venerable TMS1000—Texas Instrument's 4bit microcontroller, first ever in the world. Schematics of that clock are offered here. These have not been reverse engineered, but are newly drawn, faithful reproductions of the factory schematics, which I happen to possess:

Logic and Display
Power Supply

For additional information, follow these links:

since 17JUL07

Corey Hatch <hatch@cs.utah.edu>