Details of the Diehl Combitronic and Algotronic

Paper Tape used for booting Combitronic logic boards

These two pictures show some details from the Combitronic. In the picture on the left hand you see the metallic paper tape that is used for booting the device. It is driven by the engine from the printer. The picture on the right hand shows germanium transistors on the upper board and ceramic ROM ICs on the lower board.

It is quite interesting to see DIEHL improving quite slowly but continuing their hardware: The successor model DIEHL Algotronic (1973/74) featured 2x 21 shift registers with each 512 bits storage capacity instead of the delay line. Thus the device had about 20 kbit storage capacity, so the metallic boot tape could be extended: The new boot tape had 3 tracks (including one timing track). While the first track was read in while moving the tape forward, the second one was read in while rewinding the tape. This "boot device" contained micro programs for scientifical functions (sin, cos, tan, ln, exp, etc.). If the computer was intended for e.g. statistical functions, it needed another boot tape.
These Diehl computers look like the Combitronic, but they are equipped with a few more keys. All in all the hardware architecture from this desk computer was obsolete, even for that time. It was partily still made using germanium transistors. After these computers, Diehl built the completely new computer "Alphatronic, DS 300, DS 400" that is no more interesting for our museum.