page_title: Pravetz computers
section_title: 8-bit architecture
hierarchical_section_title: Pravetz computers / Model line / 8-bit architecture
caption_attribution_description: Компьютерный класс школы № 2 на Чкаловском посёлке, первая зимняя детская компьютерная школа (1985—86), компьютеры «Правец 82». С компьютерами знакомятся неизвестные школьные работники. Зимой в этом классе велись занятия для детей и для взрослых. Экзаменов не было: дети отчитывались творческими работами, а взрослые никак не отчитывались. Занятия вели молодые сотрудники Института программных систем: Пинчуки, Hестеровы, Грязновы, Вячеслав Крюков, Леонас, Люся Гайдар, Чернышенко.
context_page_description: Pravetz were Bulgarian computers, manufactured mainly in the town of Pravetz. Some components and software were produced in Stara Zagora, Plovdiv, and other Bulgarian cities.
context_section_description: Except for the Oric-derived 8D (and possibly the IMKO-1), all the Pravetz 8-bit systems are largely compatible with the popular Apple II and its successors, with the exception that they offer Cyrillic fonts and some other improvements compared to Apple.
  IMKO-1 — First Bulgarian personal computer. Used a clone of the 6502 CPU 1 MHz CPU, and 16/4 KB RAM/ROM. The storage media is a cassette recorder. It had a metal case and very large and heavy linear power supply. The ROM was an exact copy of the Apple 2 ROM (the only change was the name).
  Pravetz 82 (IMKO-2) - 82 is the model year. BASIC interpreter, RAM/ROM - 48/12 KB; CPU Synertek 6502 /1 MHz. The storage is improved due to the availability of (optional) 5.25" floppy disk drive(s). They had yellow plastic case and black keyboards. The later revisions used switching power supplies. ROM and schematics were not changed and were identical to those of the Apple II. A lot of the chips used were Bulgarian and Soviet substitutes (clones) of the original chips. Pravetz 82 was relatively reliable - most of the hardware problems were due to the widespread use of sub-standard quality IC sockets, mainly used for the DRAM chips.
  Pravetz 8М - Integrated second CPU Zilog Z80A at 4 MHz to be able to run CP/M and its software. The military version features integrated terminal design. It was essentially a version of Apple II+ with the optional CP/M card integrated on the motherboard. It had 64K of RAM on-board, a switching power supply and an off-white plastic case with an improved design.
  Pravetz 8E - Industrial model based on the original Pravetz 82 architecture plus some memory extensions
  Pravetz 8А - Uses Bulgarian-made chipset СМ 630, memory could be expanded up to 1 Mb using optional memory card, accessible in 64Kb banks. It was a nearly identical clone of Apple //e on electrical diagrams and ROM content levels. The case was similar to the one used for the 8M model. The keyboard was improved with arrow buttons, and the Char table included Cyrillic upper and lower case symbols. This was the most advanced model with the greatest level of upgradeability.
  Pravetz 8С - "streamlined version" of the 8А model. 128 KB RAM integrated, but not expandable. Fewer slots, but all essential controllers were integrated on the motherboard -  Parallel (Centronics) interface, FDD controllers, Joystick and sometimes with RS-232. A version of 8C is the Pravetz 8VC, which features a terminal-like design.
  Pravetz 8D - 8 bit home computer, based on 6502 and VIA 6522. It used a TV set instead of a computer monitor. Not compatible with Pravetz 82 but inherits its architecture from the French Oric Atmos home computers and compatible with their software.
caption: Pravetz 82 computer in school class in Russia
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