The TELEFUNKEN DEX102 Digitalzusatz


The DEX102

The so called "Digitalzusatz" DEX102 is an extension for TELEFUNKEN's 700 line of desk top analog computers. In conjunction with an analog computer like the RA742 the DEX102 turns the system into a hybrid computer, i.e. a combination of an analog computer and a digital computer. The DEX102 is not a computer in itself - it is just a collection of diode based and and or gates with a couple of amplifiers, inverters, delay lines and control trunk lines which connect to the analog computer's control circuits.

Like its associated analog computer the DEX102 features a removable patch panel which is shown in the picture above. The color coded plugs simplify programming quite reasonable.

The overall system:

The left picture below shows the top view of the DEX102 system. On the left is the card cage holding the (few) printed circuit cards. The power supply is located on the right side of the system. The picture on the right shows the back of the patch panel. All of the logical functions are implemented using diodes - nothing else. A four input AND gate is built from five (!) diodes. So the main components of the system are solid state diodes.

Circuit boards:

The picture below left shows a circuit board holding four individual flip flops with JK characteristic. The picture on the right shows a circuit board containing six amplifiers (inverters).

On the left the clock generator circuit can be seen while the picture on the right shows a circuit board holding four adjustable delay lines.

A counter program:

To give an impression of how a program for the DEX102 looks like the picture below shows a three bit counter with some special circuitry to reset the counter after reaching the state 5, so this program counts from 0 to 5 and restarts at 0 again.