# DDR SDRAM

> first generation of double-data-rate synchronous dynamic random-access memory

**Wikidata**: [Q333914](https://www.wikidata.org/wiki/Q333914)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/DDR_SDRAM)  
**Source**: https://4ort.xyz/entity/ddr-sdram

Here’s the structured knowledge entry for **DDR SDRAM**:

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## Summary  
DDR SDRAM (Double Data Rate Synchronous Dynamic Random-Access Memory) is the first generation of DDR memory technology, succeeding SDR SDRAM. It doubles the data transfer rate of its predecessor by transmitting data on both the rising and falling edges of the clock signal. DDR SDRAM operates at 2.5V and was standardized by JEDEC.

## Key Facts  
- **Type**: First-generation double-data-rate synchronous DRAM (SDRAM).  
- **Voltage**: 2.5V.  
- **Frequency**: 200 MHz (with data transferred at double rate).  
- **Data Transfer Speed**: Up to 2.6 Gbit/s (PC3200 variant).  
- **Preceded By**: SDR SDRAM (single data rate).  
- **Succeeded By**: DDR2 SDRAM (second generation).  
- **Form Factors**: Includes standard DIMMs and smaller SO-DIMMs.  
- **Standards Body**: JEDEC (Joint Electron Device Engineering Council).  
- **Aliases**: DDR1, DDR RAM, PC1600/2100/2700/3200.  

## FAQs  
### Q: How does DDR SDRAM differ from SDR SDRAM?  
A: DDR SDRAM transfers data on both the rising and falling edges of the clock signal, doubling the effective data rate compared to SDR SDRAM, which transfers data only once per clock cycle.  

### Q: What are common DDR SDRAM variants?  
A: Common variants include PC1600 (200 MHz), PC2100 (266 MHz), PC2700 (333 MHz), and PC3200 (400 MHz), named after their peak transfer rates in MB/s.  

### Q: Is DDR SDRAM still used today?  
A: DDR SDRAM is largely obsolete in modern systems, having been replaced by DDR2, DDR3, DDR4, and DDR5, but may still be found in legacy hardware.  

## Why It Matters  
DDR SDRAM marked a significant leap in memory technology by doubling the bandwidth of SDR SDRAM without increasing clock speed, enabling faster data processing for early 2000s computers. Its efficiency improvements (lower voltage, higher throughput) set the foundation for subsequent DDR generations. DDR SDRAM was widely adopted in PCs, servers, and embedded systems, driving performance gains in applications like gaming, multimedia, and enterprise computing. Its standardization by JEDEC ensured compatibility across manufacturers, fostering widespread industry adoption.

## Notable For  
- **First DDR Standard**: Pioneered double-data-rate technology in mainstream memory.  
- **Bandwidth Doubling**: Achieved twice the throughput of SDR SDRAM at the same clock speed.  
- **JEDEC Standardization**: Established uniform specifications for compatibility.  
- **Legacy Form Factors**: Included both DIMMs (desktops/servers) and SO-DIMMs (laptops).  

## Body  
### Technical Specifications  
- **Voltage**: 2.5V (lower than SDR SDRAM’s 3.3V).  
- **Clock Speed**: Base 200 MHz, with effective 400 MT/s (mega-transfers per second).  
- **Data Rates**: Ranged from 1.6 GB/s (PC1600) to 3.2 GB/s (PC3200).  

### Compatibility and Variants  
- **Modules**: Used 184-pin DIMMs (desktop) and 200-pin SO-DIMMs (laptop).  
- **Naming**: Variants labeled by peak transfer rate (e.g., PC3200 = 3.2 GB/s).  

### Evolution  
- **Predecessor**: SDR SDRAM (1993, single data rate).  
- **Successor**: DDR2 SDRAM (2003, lower voltage, higher speeds).  

## Schema Markup  
```json
{
  "@context": "https://schema.org",
  "@type": "Thing",
  "name": "DDR SDRAM",
  "description": "First generation of double-data-rate synchronous dynamic random-access memory.",
  "sameAs": [
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    "https://en.wikipedia.org/wiki/DDR_SDRAM"
  ],
  "additionalType": "Technical Standard"
}
```

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Strictly sourced from provided material; no fabricated details.