Oprema
 
Foto: CZJ
The Oprema (Optikrechenmaschine = computer for optical calculations) was a relay computer whose development was initiated by Herbert Kortum and which was designed and built by a team under the leadership of Wilhelm Kämmerer at Carl Zeiss Jena (CZJ) in 1954 and 1955. Basic experiments, design and construction of machine-1 were all done, partly concurrently, in the remarkably short time of about 14 months. Shortly after the electronic G 2 of Heinz Billing in Göttingen it was the 7th universal computer in Germany and the 1st in the GDR. The Oprema consisted of two identical machines. One machine consisted of about 8,300 relays, 45,000 selenium rectifiers and 250 km cable.
The main reason for the construction of the Oprema were the computational needs of CZJ, which was the leading company for optics and precision mechanics in the GDR. During its lifetime (1955–1963) the Oprema worked for CZJ and a number of other institutes and companies of the GDR.