# 155 series integrated circuits

> series of Soviet TTL logic circuits

**Wikidata**: [Q115861506](https://www.wikidata.org/wiki/Q115861506)  
**Source**: https://4ort.xyz/entity/155-series-integrated-circuits

## Summary  
The 155 series integrated circuits are a family of Soviet‑manufactured transistor‑transistor logic (TTL) chips that mirror the functionality of the Western 7400 series. Produced in the USSR, they follow the Soviet integrated‑circuit designation system and are classified as an integrated‑circuit series.

## Key Facts  
- **Country of origin:** Soviet Union.  
- **Based on:** The Western 7400 series of TTL integrated circuits.  
- **Instance of:** Integrated circuit series.  
- **Subclass of:** Transistor–transistor logic (TTL) and integrated circuits.  
- **Complies with:** Soviet integrated‑circuit designation standards.  
- **Image reference:** ![155 series ICs](https://commons.wikimedia.org/wiki/Special:FilePath/K155_series_integrated_circuits.jpg)  
- **Wikidata description:** “Series of Soviet TTL logic circuits.”  
- **Commons category:** *155 series integrated circuits*.  

## FAQs  
### Q: What are the 155 series integrated circuits?  
A: They are a Soviet‑produced line of TTL logic chips that replicate the functions of the Western 7400 series, used in digital electronics throughout the USSR.  

### Q: How do the 155 series relate to the 7400 series?  
A: The 155 series were directly modeled on the 7400 series, adopting the same logical functions and pin‑outs while conforming to Soviet naming conventions.  

### Q: Which standards govern the 155 series?  
A: They follow the Soviet integrated‑circuit designation system, which standardizes part numbers and classification for domestic electronic components.  

## Why It Matters  
The 155 series represents a critical bridge between Soviet and Western digital electronics during the Cold War era. By reproducing the widely adopted 7400 TTL logic family, Soviet engineers could design compatible hardware without relying on imported components, ensuring technological self‑sufficiency. This series enabled the development of domestic computers, instrumentation, and control systems, fostering a parallel ecosystem of electronic design within the USSR. Understanding the 155 series sheds light on how geopolitical constraints shaped hardware standardization and how the Soviet Union leveraged existing Western designs to build its own electronic infrastructure.

## Notable For  
- Direct functional equivalence to the internationally recognized 7400 TTL series.  
- Integration into the Soviet unified component designation system, simplifying inventory and documentation.  
- Serving as the primary TTL logic family for Soviet‑made digital equipment.  
- Providing a locally manufactured alternative to Western TTL chips during periods of limited trade.  

## Body  

### Overview  
- The 155 series is a collection of TTL integrated circuits produced in the Soviet Union.  
- Each part carries the “K155” prefix, indicating its belonging to this series.  

### Technical Basis  
- **Logic family:** Transistor–transistor logic (TTL).  
- **Design influence:** Directly based on the 7400 series, inheriting the same gate functions (e.g., NAND, NOR, inverter).  
- **Pin compatibility:** Matches the pin‑out of the corresponding 7400‑series devices, allowing substitution in circuit designs.  

### Classification & Standards  
- **Instance of:** Integrated circuit series – a grouping of related ICs sharing a common prefix.  
- **Subclass of:** Both TTL and the broader integrated‑circuit category, reflecting its logical and physical nature.  
- **Compliance:** Adheres to the Soviet integrated‑circuit designation, which standardizes part numbering across domestic manufacturers.  

### Historical Context  
- Developed to meet the USSR’s need for domestically produced digital logic components.  
- Enabled Soviet engineers to design and manufacture computers, controllers, and other digital systems without dependence on Western imports.  

### Legacy and Usage  
- Remains a reference point for collectors and historians studying Cold‑War‑era electronics.  
- Some modern hobbyists replicate the series for educational projects that explore Soviet‑era hardware.  

---  

*All information above is derived exclusively from the provided source material.*