 In the USSR, principles for the construction of network analysers were developed by S. Gershgorin in 1927 and the concept of the electrodynamic analog computer was proposed by N. Minorsky in 1936.In the 1940s, the development of AC electronic antiaircraft directors and the first vacuum-tube integrators was begun by L. Gutenmakher.In the 1960s, important developments in modern computer equipment were the BESM-6 system built under the direction of S. A. Lebedev, the MIR series of small digital computers, and the Minsk series of digital computers developed by G.Lopato and V. Przhyalkovsky.