# US Patent 4,121,298: Central Processing Unit for Numbers Represented in the System of Residual Classes

Compiled by [Robin Monks](https://coldwar.tech/about), a Cold War archival expert.

*The most detailed public document describing a complete CPU architecture built on the Residue Number System, filed internationally by Akushsky and four co-inventors in 1976.*

## Metadata

| Field | Value |
|-------|-------|
| Document Type | blueprint-schematic |
| Creator | Israel Yakovlevich Akushsky, Vladimir Mikhailovich Burtsev, Bulat Esenovich Duisenov, Ivan Timofeevich Pak, Anurbek Orymbekovich Zhautykov |
| Date | 1978-10-17 |
| Classification | UNCLASSIFIED |
| Document ID | US4121298A |
| Original Language | english |

## Related

- [Duga radar](https://coldwar.tech/systems/duga-radar) (Systems)
- [Residual Computing](https://coldwar.tech/technologies/residual-computing) (Technologies)
- [K340A](https://coldwar.tech/technologies/k340a) (Technologies)

Tags: patent, residue-number-system, rns, cpu-architecture, modular-arithmetic, k340a, akushsky, soviet-computing

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Canonical URL: https://coldwar.tech/archive/documents/us-patent-4121298a
Last updated: 2026-07-15