Full speed null modem cable for EPSON HX-20

To transfer software for the EPSON HX-20 from the PC, a so-called null modem cable is required. These cables usually have 9 pin D-Sub connectors at both ends. Therefore it is necessary to cut such a cable in the middle to solder a round 8 pin DIN connector to the open end.

For the HX-20 there are basically two variants for a data transmission cable. The simple variant requires only 3 cable wires, but has the disadvantage that no handshake or data flow control is possible. Ergo, only a low transfer rate is possible. I already presented such a simple cable here some time ago.

Here I now describe the more complex variant of a null modem cable, which is also suitable for higher transmission rates with data flow control. This allows a much more stable connection between PC and HX-20.

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Wessi goes east: How I got to know the Robotron PC 1715

*Wessi [‘wes-see] is the flippant term for a West German citizen.

“With the production of the personal computer 1715 the VEB Robotron Büromaschinenwerk Ernst Thälmann Sömmerda makes an important contribution to the realization of the decisions of the XI party congress of the SED. By realizing the commitment of the office machine workers to provide the national economy with 10,000 personal computers in addition to the plan by the end of 1986, the acceleration of scientific-technical progress for the intensification of national economic processes and the increase of labor productivity is effectively supported.”

Source: Handbook “The Personal Computer 1715”, Publisher: VEB Kombinat Robotron, several authors, ISBN 3-349-00231-5, Issue: 1986/1987).

That’s how it was in the GDR back then! The leadership of the state power, the Unity Party SED of the German Democratic Republic, submitted a plan every five years in which it was determined what was to be developed and produced in the factories of the East German combines. Of course, the importance of computer technology was also recognized in the former Eastern Bloc, which included the then GDR, and so the company very soon began its own developments in this area.

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