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A historical past of the EPROM within the Soviet Union

A historical past of the EPROM within the Soviet Union

2023-01-20 08:29:56

Dov Frohman

In 1971 Intel got here out with the primary reminiscence that might be not solely programmed by the consumer, however might be erased with UV gentle and programmed once more. This was the 1701 EPROM (rapidly revised into the 1702 EPROM and 1702A). It was 2048 bits (256×8), used PMOS, and required three voltage (+5V, +12V and -12V) to function, and every knowledge line required a strobed -48V pulse for programming.

The 1701 was launched to the world within the Could 10, 1971 situation of Electronics Journal in an article written by Dov Frohman, the inventor of the EPROM.  At this time Intel is extra identified for, and remembered by their microprocessors, however till the early 1980’s it was EPROM’s that carried the corporate.  They accounted for the most important share of income at Intel for over a decade.


Soviet K505RR1 – 1978

Intel 1701 – Unmarked


The primary EPROM chip produced within the Soviet Union was the K505RR1, developed by the Kyiv Analysis Institute of Microdevices and manufactured by the Kvazar manufacturing unit in Kyiv, Ukraine. The chip is a 2048-bit (256×8) electrically programmable read-only reminiscence with ultraviolet erasure. It’s an analogue of the 1702А.
They supported as much as 20 (they wore out fairly rapidly)  overwrite cycles and had a knowledge retention interval in on state of not much less 5000 hours. This is among the solely EPROM chips manufactured within the flat pack bundle. NEC made a 2Mbit flat pack EPROM within the Nineteen Nineties, fairly an odd beast.


Analogue of the i2708. The microcircuit is a read-only reminiscence gadget with a capability of 8 Kbit (1024х8). Provide voltages of  12v, 5v, -5v. Knowledge Retention interval in on state shouldn’t be much less 15000 hours. Variety of write cycles a minimum of 100. (a pleasant enchancment over the earlier technology)

Microcircuits have been manufactured at two factories: Novosibirsk Manufacturing unit Vostok and Novosibirsk Electrovakuum Manufacturing unit (NEVZ). The ‘3’ emblem is an export model.

NEVZ – 1984


NEVZ navy grade model(with out letter Okay + rhombus) -1986

Vostok – 1982


Export – 1986


Export – 1987


On microcircuits with a metallic cowl, you possibly can see that part of the conductor connecting this cowl and GND pin has been mechanically eliminated. In electrochemical coating, it’s needed that each one surfaces on which gold is deposited on this case be related to one another.  However the K573RF1 chip has three energy provides. And minus 5 volts is utilized to the die substrate. A part of the conductor has been eliminated to keep away from a doable quick circuit.

It’s clearly seen that the die of K573RF1 is split into two reminiscence blocks.

Within the manufacture of dies, it occurs that a number of reminiscence cells change into broken. The producer blocks entry to broken a part of the die by connecting one or two enter addresses to floor or an influence provide. Both ensures the operation of solely half of the info bus of the microcircuit. K573RF11, K573RF12 have an data capability of 4 Kbit (512×8) ,  K573RF13, K573RF14- 4 Kbit (1024×4).




(I would not have any instance of the 573RF11 or 573RF12 however would love so as to add some)


Analog of the i2716 with capability of 16 Kbit (2048х8). Provide voltage +5v. Knowledge retention interval in on state shouldn’t be much less 25000 hours. Variety of write cycles a minimum of 100.
Initially, microcircuits have been produced in white ceramic packages, the identical as these of the K573RF1. Solely the necessity to take away a part of the conductor on prime was now not there. The die’s substrate was now related to floor.

Many microcircuits have been produced with the State High quality Mark of the USSR.
You may learn extra about this right here:

On some microcircuits, you possibly can see the abbreviation OTK. That is the mark of the Technical Management Division. In economic system of the Soviet Union, Technical Management Departments (Russian: OTK) have been and are in control of high quality assurance of manufacturing. Within the late Soviet Union the OTK existed in all socialist enterprises.

Manufacturing factories are the identical that produced K573RF1. Solely within the early 90s did a brand new producer seem. Analysis and Manufacturing Cooperative «KVANT» (Latvia).

With and with out manufacturing date

A part of the K573RF2 was produced with out the producer’s emblem


Additionally, as within the case of K573RF1, there have been half-capacity K573RF2 chips. K573RF21, K573RF22 have an data capability of 8 Kbit (1024×8) , K573RF23, K573RF24- 8 Kbit (2048×4).

The K573RF2 die may be very totally different from the K573RF1 die. Now it has a single area of reminiscence cells.

By the tip of the eighties, 573RF2 microcircuits appeared in ceramic packages in terracotta shades. The bundle consists of two halves related by a glass like compound.  This was the identical as customary western ceramic DIPs of the time, simply with totally different compounds leading to a lot totally different colours.

Along with the appearance of those packages, a change of marking begins. Initially, microcircuits had the letter M of their identify ( KM573RF2). After a while, the letter M was changed by the letter S (Russian C).

These chips are marked KS573RT2. Unusually, the letter mixture RT refers to one-time programmable reminiscence chips. Different firms, together with Intel, Nationwide Semi. and Mostek, additionally resorted to portray over a part of the floor of the microcircuit with subsequent re-marking, Mainly changing EPROMs to OTP-PROMs.  Intel did this loads for his or her Dev boards.

K573RF2, not KM, not KS. The factor is that the highest of microcircuit is made from brown ceramics, and the underside is made from white. The oddity lies in the truth that the ensuing «sandwich» has the State High quality Mark.  Clearly they have been utilizing left over components.  One wonders what the totally different supplies did for warmth cycles.

Properly, the final chip of this sequence. In plastic bundle. The window for erasing is kind of small. The Soviet’s have been the one ones I do know of that managed to make a plastic bundle EPROM.  Discovering appropriate supplies that may cross UV gentle, AND be thermally suitable is difficult.


Microcircuits of this sequence are absolutely suitable with microcircuits of RF2 sequence. They have been made in different factories. All chips in ceramic packages have been manufactured on the Kvazar manufacturing unit in Kyiv.

Among the chips was made with out the manufacturing unit emblem.

Till 1988, there was a die, divided into two reminiscence blocks (made in 2 totally different sizes). After that, a die with a very totally different topology was put in.

On the finish of the eighties, there was a transition to a different kind of bundle, just like RF2 packages.

573RF5 microcircuits have been additionally produced in plastic packages. One other producer has been added to the Kvazar manufacturing unit. KVADR manufacturing unit, Chernihiv area, Ukraine.

I need to end this text with a curious truth. These are KC558RR2A/B EEPROMs.  These are Electrically Erasable components, not UV Erasable.  It was additionally produced in a bundle with a quartz window. However the die was painted over with brown lacquer. It’s not possible to erase it with ultraviolet gentle. Socialist economic system had the deliberate nature. Possibly the manufacturing unit was delayed on chip manufacturing. And this was the answer.

We’ll focus on extra SOviet EPROMs in Half 2 of the article, such beauties because the RF3 , 4 6 and eight sequence

I categorical my gratitude to Andrey Perfiliev (Andrey_cpu) and Victor Fyodorov (Victor_F) for his or her help
in writing this text.
The photographs of the dies from the positioning
Images of chips are partially taken from the positioning, in addition to from the Andrey Perfiliev and John Culver (The CPU Shack)  collections.

Written by: Vladimir Yakovlev
Edited by: John Culver (CPU Shack)



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