ISOT

• Central Institute of Computer Engineering ( Bulgarian. Central Institute of Computing Engineering, TsIIT)
• Computer Engineering Plant ( Bulgarian. Computer Engineering Plant , ZIT)
• Factory "Electronics" ( Sofia );

• factories for the production of memory devices in Plovdiv , Stara Zagora , Veliko Tarnovo and Burgas ;
• Pazardzhik magnetic disk factory;
• typewriter factory in Plovdiv;
• recording equipment factory in Samokov ;
• mechanical structures factory in Blagoevgrad ;
• PCB factory in Russ ;
• Analyst factory in Mikhailovgrad ;
• Clement Voroshilov plant, producing peripheral and radio relay systems;
• factory in Varna ;
• Plant "Office equipment" with a laboratory of technical development in Silistra ;
• Electra plant, a factory for the production of electronic components and the service of IZOT products in Sofia.
• repair factory "Kantselsarsky Mashiny" in Sofia;

ISOT also included many research institutes and technical development centers.

Bulgaria was one of the co-founders of the Council for Mutual Economic Assistance (CMEA), which was formed on January 25, 1949. By the beginning of the 60s, the extensive development of the country had exhausted its possibilities: the influx of excess population from agriculture to industry was ending, and real growth in labor productivity slowed down. There was a need to translate the intensification of the economy, that is, accelerate the pace of scientific and technological progress . At the same time, Bulgaria received loans from the Soviet Union for the construction of the most important national economic facilities, and at only 2% per annum. Payment of loans, as a rule, was made by products of enterprises built at their expense. This helped to reduce the time needed to overcome the country's technical and economic backwardness and to dynamize its economic development.

In the late 60s, it was decided to develop a high - tech electronic industry . After the signing of the Intergovernmental Agreement and the creation of the IPC on computer technology in 1969, the construction of 12 modern factories for the production of parts, assemblies and hardware of the EU computer began in the NRB. At the same time, three institutes for design work were organized. All these enterprises were created within the framework of the Ministry of Electronics and Electrical Engineering and after some time were merged in the framework of IZOT software. ^[one]

In 1970 , the Economic Council for Electronic Components was established with a directorate in Botevgrad. He united ten manufacturing enterprises, as well as research and design institutes. This council was responsible for the production of transistors, silicon diodes, integrated switches, capacitors, resistors, etc.

The main activities of Bulgarian enterprises were identified:

• development and production of computers in conjunction with NIIEVM and MPO VT (Minsk);
• development and production of magnetic disk and tape drives in conjunction with NICEVT .

Bulgarian specialists ^[2] quickly established cooperation with their Minsk colleagues, who had extensive experience in the development of computers of the Minsk series . Soon, joint teams appeared that quickly solved rather complex problems, for example:

• determination of the architecture of the machine , its microprogram control, organization and structure of channels and interface, arithmetic and logical devices, etc .;
• the use of a new integrated element base in the design of large computing devices in a third-generation system;
• design development based on a modular principle;
• the solution of complex structural and technological issues in the development of RAM ;
• creation of the basis for collaboration on design automation .

A certain negative role was played by a rather complicated separation of functions between partners and senseless bureaucratic obstacles, which often complicated or even hindered teamwork.

EC-1020

Starting from the 1970s, the basis for Bulgarian-Soviet cooperation was also the joint production of the EC-1020 computer, headed by a research institute in Minsk and the Institute of Computer Engineering in Sofia. The production of these machines at the plant them. Ordzhonikidze in Minsk and IZOT, as well as the presentation at the EU-73 exhibition in Moscow, marked an important stage in the development of the Bulgarian production of computer technology, which ultimately created the necessary conditions for the introduction of automatic data processing tools in the Bulgarian economy.

Officially it was believed that the EU-1020, EU-1022, EU-1035 models of the USSR and NRB were developed jointly. In fact (due to the inability to organize a joint team of specialists working for a long time in one place, which is necessary for the development of the processor), the documentation for these computers was developed at the NIIEVM. The Bulgarian side (CIIT) contributed to this work by accepting seconded specialists from the NIIEVM and providing them with the available information on the IBM / 360 system and computer time on model 25 of the IBM / 360 system.

Periphery

In addition to the significant investments in these enterprises made by the respective Soviet organizations, cooperation agreements were concluded and great practical assistance was provided by the Soviet Union in all production areas for many years. Thus, Bulgaria quickly took an important place among the CMEA countries - computer manufacturers, and later was able to supply a significant part of its electronic products to the USSR. In the 1980s, especially with the advent of small and personal computers, Bulgarian memory devices and IZOT magnetic disks became especially popular among Soviet consumers. It is noteworthy that, despite the rather modest experience in industrial production, the quality of Bulgarian memory devices, peripherals, etc. was quite satisfactory, and sometimes even exceeded the level of quality of similar Soviet models (the Soviet mass production began to reach a high level of quality quite late).

Bulgaria also conducted joint development with Carl Zeiss factories and Robotron in the GDR, the TESLA plant in Czechoslovakia , the MERA Networks association in Poland , with Hungary , CPP and Cuba.

According to official data, the growth of production of IZOT (which had the highest rates among other enterprises) in the 70s amounted to 30% per year. During the period of the Sixth Five-Year Plan (1970-1975), the volume of production of military equipment increased 10 times, and up to 80% of production was exported to the CMEA countries.

Computers

• ZIT-151 EIM - Facom 230-30 under license from Fujitsu
• EU-1020 ( 1972 ), EU-1022 ( 1975 ) - Unified system computers , one of the first ones produced in the socialist camp
• EC-1035 ( 1977 ) - an analogue of the IBM System / 370 , 140-160 thousand operations per second
• EC 1037 - analogue of M80 / 42 (IBM 4341 compatible)
• Isot 301 - an analogue of PDP-8
• Izot 310 - small-sized modular minicomputers
• Isot 1016 is an analogue of PDP-11 (or, according to the nomenclature of CMEA, SM-4 ), the first mass-produced mini-computer of the Elektronika plant. Delivered to the USSR, Cuba, Zimbabwe, North. Korea and others
• Isot 1055 - DEC VAX 11/730 analogue, 32-bit super-mini computer
• Isot 1055C - analogue of VAX 11/750
• Isot 1056 - analogue of VAX 11/780
• Isot-1030C - with processor compatible with Intel 8086
• Izot-1031C - monitor and computer ( Z80 / U880 processor ) in one kopus, had an 8 "floppy drive
• Isot 1036C - IBM PC- compatible, Intel 8086
• Isot 1037С - analogue of IBM PC / XT , with Intel 8088
• Isot-1039C

Other

• small tape drives (IZOT-1006, IZOT-5004 E, SM5300.01);
• floppy drives 8 "and 5.25"
• external storage devices (VZU) on removable magnetic disks EC-5052 (capacity 7.25 Mb per packet), EC-5061 (29 Mb per packet) and IZOT-1370; rack-mount module 8 "drives CM 5635.10 (two IZOT EC5074);
• IZOT floppy disks (EU 5274, etc.);

• HDD (copies of IBM : Isot SM5400 (first serial) ^[3] , SM5508 and others; series EC-5065 (A5444E - 100 Mb and A529E - 200 Mb))
• NML EC-5012 (tape drive 12.6 mm wide

• word processing device IZOT-1002-C (late 1970s).
• alphanumeric printing devices IZOT-132-D and CPU MINIPRINT-45 and MINIPRINT-77 (for accounting and management systems);
• typewriters Maritsa
• various microprocessors .

• Pravets (computer)
• Robotron (GDR)
• History of Computer Engineering

• Computers of the CMEA countries
• Diskette IZOT EU 5274 - 8 inches at the Museum of Computer Technology
• ISOT 1030C, 1031C, 1036C and 1039C // bulgariancomputers.com (bulgarian)