Razdan

a city (until 1959 the settlement of Akhta) under republic jurisdiction and administrative center of Razdan Raion, Armenian SSR. Located on the Razdan River, a tributary of the Araks. Railroad station 50 km north of Yerevan. Population, 33,000 (1974).

Razdan has a mining and chemical combine engaged in the complex processing of local nepheline syenites, a state regional power plant, a heat and electric power plant, the Atarbekian Hydroelectric Power Plant, a large-panel housing combine, a refrigeration combine, a branch of a clothing factory, a milk plant, and a brewery. There is also an industrial and technological technicum in the city.

(also Zanga), a river in the Armenian SSR, a left tributary of the Araks River (Kura River basin). The Razdan River is 141 km long and drains an area of 2,560 sq km (including the basin of Lake Sevan, 7,310 sq km). It rises in Lake Sevan and flows through a mountain valley; the lower Razdan flows across the Ararat Plain. The gradient is 1,097 m (1.8 m/km). Under natural conditions, the average flow rate is approximately 2 cu m per sec at the source and 17.9 cu m per sec near the mouth. A series of six hydroelectric power plants has been constructed on the river. After their construction, the flow rate at the source increased to 44.5 cu m per sec because of the decrease in water reserves in Lake Sevan. In order to prevent the water level of Lake Sevan from lowering even more, the discharge of water was reduced to 16 cu m per sec in 1965. The waters of the Razdan are also used for irrigation. The cities of Sevan, Razdan, Charentsa-van, Arzni, and Yerevan are situated on the river.

a series of second-generation general-purpose electronic digital computers developed at the Yerevan Scientific Research Institute of Mathematical Machines. The models R-2 and R-3 have been the most popular computers in the series.

The R-2 was designed for both scientific and engineering problems and was produced from 1961 until 1968. It could perform about 5,000 operations per sec; the addition time was 120 microseconds (μsec), and the multiplication time was 400 μsec. The capacity of the internal memory was 2,048 words, and the access cycle time was 20 μsec The external memory was on magnetic tape and had a capacity of 120,000 words. The R-2 had a two-address instruction repertory, floating-point number representation, and a word length of 36 bits. Data input was by punch tape, which was read by a photoelectric reading device at 35 words per sec. Data output was by a numeric printer, which had a speed of 20 lines per sec, or by punch tape.

The R-3 was designed for problems in science, engineering, economic planning, statistics, and accounting. It was developed in 1966. The basic characteristics of the R-3 include a module structure, the possibility for the expansion of the internal memory by the addition of storage blocks, hardware check with the correction of single errors, simultaneous operation of the data input-output units and the arithmetic unit, and an extensive interrupt system. The speed of the R-3 is about 20,000 operations per sec; the addition time is 40 μsec, and the multiplication time is 90 μsec. The capacity of the internal memory is 16,384 to 32,768 words, and the access cycle time is 8 μsec. The external memory makes use of magnetic tape, with a capacity of 320,000 words, and magnetic drums, with a capacity of 7,500 words. Up to 16 external memory units can be connected to the machine. The R-3 has a two-address instruction repertory, floating-point number representation, and a word length of 48 bits. Data input is by punch tape at 1,000 lines per sec or by punch cards at 700 cards per min. Data output is by an alphanumeric printer at 400 lines per min, by punch cards at 100 cards per min, or by punch tape at 20 lines per sec. The R-3 can execute the programs of several users either on a real-time or time-sharing basis.