DEC yesterday emerged as the surprise partner for Mannesmann AG in its troublesome Mannesmann Kienzle Datensysteme, plus the Procad GmbH and PCS GmbH divisions of Mannesmann Kienzle. DEC has agreed to invest $230m for a 65% stake in an new company to be formed out of the loss-making computer businesses, which aim mainly at the small systems and manufacturing markets. Mannesmann will retain 35% of the new company. Headquartered in Villingen, Germany, it will be called Digital-Kienzle Computer Systeme GmbH and Co KG, and the partners hope to have it up and running as of January 1 – but regulatory approvals may delay that. The $230m is its largest external investment in DEC’s 33-year history, so it must do a lot to enhance the company’s position in the German market. Mannesmann acquired Kienzle, a sleepy Black Forest family firm that made visible record computers and taximeters, in 1982. It is now the second- largest domestic computer supplier in Germany. Digital-Kienzle will have sales offices in 28 German ci ties and in other European count ries and claims to have one of the premier Unix software development organisations in Germany. The West German subsidiary of DEC had fiscal 1990 sales of $835m and in 1989, Kienzle had sales of $448m. Mann esmann had been talking to Fujitsu Ltd, but the Japanese company is decided simply to settle for ICL.