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The KR580VM80A () is a
Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
microprocessor A microprocessor is a computer processor (computing), processor for which the data processing logic and control is included on a single integrated circuit (IC), or a small number of ICs. The microprocessor contains the arithmetic, logic, a ...
, a clone of the
Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California, and Delaware General Corporation Law, incorporated in Delaware. Intel designs, manufactures, and sells computer compo ...
8080 The Intel 8080 is Intel's second 8-bit microprocessor. Introduced in April 1974, the 8080 was an enhanced successor to the earlier Intel 8008 microprocessor, although without binary compatibility.'' Electronic News'' was a weekly trade newspa ...
CPU A central processing unit (CPU), also called a central processor, main processor, or just processor, is the primary processor in a given computer. Its electronic circuitry executes instructions of a computer program, such as arithmetic, log ...
. Different versions of this CPU were manufactured beginning in the late 1970s, the earliest known use being in the SM1800 computer in 1979. Initially called the K580IK80 (К580ИК80), it was produced in a 48-pin planar metal-ceramic package. Later, a version in a PDIP-40 package was produced and was named the KR580IK80A (КР580ИК80А). The pin layout of the latter completely matched that of Intel's 8080A CPU. In 1986 this CPU received a new part number to conform with the 1980
Soviet integrated circuit designation The soviet integrated circuit designation is an industrial specification for encoding the names of integrated circuits manufactured in the Soviet Union and the Post-Soviet states. 25 years after the dissolution of the Soviet Union, a number of #M ...
and became known as the KR580VM80A (КР580ВМ80А), the number it is most widely known by today (the KR580VV51A and KR580VV55A peripheral devices went through similar revisions). Normal
clock frequency Clock rate or clock speed in computing typically refers to the frequency at which the clock generator of a Microprocessor, processor can generate Clock signal, pulses used to Synchronization (computer science), synchronize the operations of it ...
for the K580IK80A is 2 MHz, with speeds up to 2.5 MHz for the KR580VM80A. The KR580IK80A was manufactured in a 6 
μm The micrometre (Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a unit of length in the International System ...
process. In the later KR580VM80A the feature size was reduced to 5 μm and the die became 20% smaller.


Technology and support chips

The KR580VM80A was manufactured with an n-MOS process. The pins were electrically compatible with TTL logic levels. The load capacity of each output pin was sufficient for one TTL input. The output
capacitance Capacitance is the ability of an object to store electric charge. It is measured by the change in charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized are two closely related ...
of each control and data pins was ≤ 100 pF each. The family consists of the following chips: For brevity, the table above lists only the chip variants in a plastic DIP (prefix ''КР'') as well as the original planar package (prefix ''К''). Not listed separately are variants in a ceramic DIP (prefix ''КМ'' for commercial version and prefix ''М'' or no prefix for the military version) or export variants (prefix ''ЭКР'') in a plastic DIP but with a pin spacing of one tenth of an inch. For the KR580VM1 (''КР580ВМ1'') see Further development below. Several integrated circuits in the K580 series were actually intended for other microprocessor families: the KR580VR43 (''КР580ВР43'' — Intel 8243) for the K1816 family (
Intel MCS-48 The MCS-48 microcontroller series, Intel's first microcontroller, was originally released in 1976. Its first members were 8048, 8035 and 8748. The 8048 is arguably the most prominent member of the family. Initially, this family was produced ...
) and the KR580GF84 (''КР580ГФ84'' —
Intel 8284 The Intel 8284 is a clock oscillator chip developed primarily for supplying clock signals for the Intel 8086, Intel-8086/Intel 8087, 8087/Intel 8088, 8088/Intel 8089, 8089 series of processors. The commercial variant of the chip comes in 18-pin Du ...
) / KR580VG88 (''КР580ВГ88'' —
Intel 8288 The Intel 8288 is a bus controller designed for Intel 8086/8087/8088/ 8089. The chip is supplied in 20-pin DIP package. The 8086 (and 8088) operate in maximum mode, so they are configured primarily for multiprocessor operation or for working with ...
) / KR580VB89 (''КР580ВБ89'' —
Intel 8289 The Intel 8289 is a Bus arbiter designed for Intel 8086/8087/ 8088/ 8089. The chip is supplied in 20-pin DIP package. The 8086 (and 8088) operate in maximum mode, so they are configured primarily for multiprocessor operation or for working with co ...
) for the K1810 family (
Intel 8086 The 8086 (also called iAPX 86) is a 16-bit computing, 16-bit microprocessor chip designed by Intel between early 1976 and June 8, 1978, when it was released. The Intel 8088, released July 1, 1979, is a slightly modified chip with an external 8-b ...
). Additionally, most devices in the K580 series could be used for the K1810 series as well.


KR580VM80A vs. Intel 8080A

While the Soviet clone appears to be fully software-compatible with Intel 8080A, there is a slight difference between the two processors'
interrupt In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted ...
handling logic, which looks like an error in the KR580VM80A's
microcode In processor design, microcode serves as an intermediary layer situated between the central processing unit (CPU) hardware and the programmer-visible instruction set architecture of a computer. It consists of a set of hardware-level instructions ...
. If a CALL instruction
opcode In computing, an opcode (abbreviated from operation code) is an enumerated value that specifies the operation to be performed. Opcodes are employed in hardware devices such as arithmetic logic units (ALUs), central processing units (CPUs), and ...
is supplied during INTA cycle and the INT input remains asserted, the KR580VM80A does not clear its internal Interrupt Enable flag, despite the INTE output going inactive. As a result, the CPU enters a microcode loop, continuously acknowledging the interrupt and pushing the PC onto the
stack Stack may refer to: Places * Stack Island, an island game reserve in Bass Strait, south-eastern Australia, in Tasmania’s Hunter Island Group * Blue Stack Mountains, in Co. Donegal, Ireland People * Stack (surname) (including a list of people ...
, which leads to
stack overflow In software, a stack overflow occurs if the call stack pointer exceeds the stack bound. The call stack may consist of a limited amount of address space, often determined at the start of the program. The size of the call stack depends on many fa ...
. In a typical hardware configuration this phenomenon is masked by the behavior of 8259A interrupt controller, which deasserts INT during INTA cycle. The Romanian MMN8080 behaves the same as the KR580VM80A; no other 8080A clones seem to be affected by this error.


Applications

The KR580VM80A was popular in
home computer Home computers were a class of microcomputers that entered the market in 1977 and became common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a s ...
s,
computer terminal A computer terminal is an electronic or electromechanical hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system. Most early computers only had a front panel to input or display ...
s, industrial controllers. Some of the examples of its successful application are: * KUVT Korvet educational computer *
Radio-86RK The Radio-86RK () is a build-it-yourself home computer designed in the Soviet Union. It was featured in the popular ''Radio'' () magazine for radio hams and electronics hobbyists in 1986. The letters RK in the title stands for the words ''Radio ...
(Радио 86РК), probably the most popular amateur
single-board computer A single-board computer (SBC) is a complete computer built on a single circuit board, with microprocessor(s), memory, input/output (I/O) and other features required of a functional computer. Single-board computers are commonly made as demonst ...
in the Soviet Union *
Micro-80 The Micro-80 () was the first do-it-yourself home computer in the Soviet Union. Overview Schematics and information were published in the local DIY electronic magazine ''Radio'' in 1983. It was complex, using an KR580VM80A-based system (a clone o ...
( Микро-80 in Russian), Radio 86RK's predecessor * Orion-128 ( Орион-128 in Russian), Radio 86RK's successor, which had a graphical display *
Specialist (computer) The Specialist () is a DIY computer designed in Soviet Union. Its description was published in ''Modelist-Konstructor'' (), a magazine for scale model builders in 1987. It was the first such publication in a magazine not oriented on electronics. ...
, similar to Orion-128 * UT-88 amateur computer * SM 1800 industrial mini computer *
Vector-06C Vector-06C () is a home computer with unique graphics capabilities that was designed and mass-produced in USSR in the late 1980s. History Vector-06C was created by Soviet engineers Donat Temirazov and Alexander Sokolov from Kishinev, Moldov ...
home computer, where KR580VM80A is overclocked to 3 
MHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base u ...
by design * TIA-MC-1 (ТИА-МЦ-1) arcade machine *
Juku E5101 Juku E5101 was a personal computer targeted at Estonian schools which was released in 1988. The computer had monochrome display, a mouse and basic LAN capabilities, it ran CP/M 2.2 based EKDOS and had a Soviet Intel 8080A clone KR580VM80A for CPU ...
educational computer designed in
Estonia Estonia, officially the Republic of Estonia, is a country in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea across from Sweden, to the south by Latvia, and to the east by Ru ...
* Maestro (Маэстро) Soviet four voice hybrid
analog synthesizer An analog synthesizer () is a synthesizer that uses Analogue electronics, analog circuits and analog signals to generate sound electronically. The earliest analog synthesizers in the 1920s and 1930s, such as the Trautonium, were built with a var ...
keyboard


Further development

Mirroring the development in the West, where the Intel 8080 was succeeded by the
binary compatible Binary-code compatibility (binary compatible or object-code compatible) is a property of a computer system, meaning that it can run the same executable code, typically machine code for a general-purpose computer central processing unit (CPU), ...
Intel 8085 The Intel 8085 ("''eighty-eighty-five''") is an 8-bit microprocessor produced by Intel and introduced in March 1976. It is software-binary-code compatibility, binary compatible with the more-famous Intel 8080. It is the last 8-bit microprocesso ...
and
Zilog Z80 The Zilog Z80 is an 8-bit computing, 8-bit microprocessor designed by Zilog that played an important role in the evolution of early personal computing. Launched in 1976, it was designed to be Backward compatibility, software-compatible with the ...
as well as the
source compatible Source-code compatibility (source-compatible) means that a program can run on computers (or operating systems), independently of binary-code compatibility and that the source code is needed for portability. The source code must be compiled befo ...
Intel 8086 The 8086 (also called iAPX 86) is a 16-bit computing, 16-bit microprocessor chip designed by Intel between early 1976 and June 8, 1978, when it was released. The Intel 8088, released July 1, 1979, is a slightly modified chip with an external 8-b ...
, the Soviet Union produced the IM1821VM85A (''ИМ1821ВМ85А'', actually the CMOS version Intel 80C85), KR1858VM1 (''КР1858ВМ1''), and K1810VM86 (''К1810ВМ86''), respectively. The 580VM80 is still shown on the price list of 1 October 2024 of the "Kvazar" plant in
Kyiv Kyiv, also Kiev, is the capital and most populous List of cities in Ukraine, city of Ukraine. Located in the north-central part of the country, it straddles both sides of the Dnieper, Dnieper River. As of 1 January 2022, its population was 2, ...
together with various support chips of the K580 series. Another development, the KR580VM1 (''КР580ВМ1''), has no western equivalent. The KR580VM1 extends the Intel 8080 architecture and is binary compatible with it. The extensions differ, however, from both the Intel 8085 and the Zilog Z80. The KR580VM1 extends the address range from 64KB to 128KB. It adds two registers, H1 and L1, that can be used instead of H and L. Several 16-bit arithmetic instructions were added as well (DAD, DSUB, DCOMP). Just like the Intel 8085 and the Zilog Z80, the KR580VM1 needs only a single +5V power supply instead of the three voltages required by the KR580VM80A. The maximum clock frequency was increased from 2 MHz to 5 MHz while the power consumption was reduced from 1.35W to 0.5W, compared to the KR580VM80A.


See also

*
Intel 8080 The Intel 8080 is Intel's second 8-bit computing, 8-bit microprocessor. Introduced in April 1974, the 8080 was an enhanced successor to the earlier Intel 8008 microprocessor, although without binary compatibility.'' Electronic News'' was a week ...
* MCS-85 Family *
List of Soviet computer systems This is the list of Soviet computer systems. The Russian abbreviation EVM (ЭВМ), present in some of the names below, means "electronic computing machine" (). List of hardware The Russian abbreviation EVM (ЭВМ), present in some of the names ...
*
Soviet integrated circuit designation The soviet integrated circuit designation is an industrial specification for encoding the names of integrated circuits manufactured in the Soviet Union and the Post-Soviet states. 25 years after the dissolution of the Soviet Union, a number of #M ...


References


External links

*
CPU World page about KR580VM80A

Reverse-engineering of KR580VM80A
{{List of Soviet microprocessors Computer-related introductions in 1979 Computing in the Soviet Union 8-bit microprocessors