# XP/S4
**Wikidata**: [Q69643835](https://www.wikidata.org/wiki/Q69643835)  
**Source**: https://4ort.xyz/entity/xp-s4-q69643835

## Summary  
XP/S4 is an Intel‑manufactured supercomputer that was listed in the TOP500 (system ID 283) in the early 1990s. It runs the OSF/1 and Tru64 UNIX operating systems, delivers up to 2.8 gigaflops (Rpeak) and 1.75 gigaflops (Rmax) of performance, and contains 56 processor cores.

## Key Facts  
- **Type:** Supercomputer (instance of supercomputer).  
- **Manufacturer:** Intel (American multinational technology company).  
- **Operating Systems:** OSF/1 (a variant of Unix) and Tru64 UNIX.  
- **TOP500 Identifier:** 283.  
- **Performance (Rmax / Rpeak):** 1.5 – 1.75 gigaflops (Rmax) and 2.8 gigaflops (Rpeak) measured in 1993 – 1994.  
- **Processor Cores:** 56 cores.  
- **First recorded performance data:** 1.5 gigaflops (Rmax) and 2.8 gigaflops (Rpeak) on 1993‑06‑01.  
- **Later performance data:** 1.75 gigaflops (Rmax) and 2.8 gigaflops (Rpeak) on 1994‑11‑01.  

## FAQs  
### Q: What is XP/S4?  
A: XP/S4 is an Intel‑built supercomputer from the early 1990s that ran Unix‑based operating systems and achieved a peak performance of 2.8 gigaflops.  

### Q: Which operating systems does XP/S4 support?  
A: XP/S4 runs OSF/1, a Unix variant developed by the Open Software Foundation, and also supports Tru64 UNIX.  

### Q: How powerful was XP/S4 compared to other machines of its time?  
A: In 1993‑1994 XP/S4 reached a maximum measured performance (Rmax) of 1.5‑1.75 gigaflops and a theoretical peak (Rpeak) of 2.8 gigaflops, earning it a place on the TOP500 list (system ID 283).  

## Why It Matters  
XP/S4 illustrates an early collaboration between Intel and the high‑performance computing community, showcasing Intel’s entry into the supercomputing market. By leveraging Unix‑based operating systems such as OSF/1 and Tru64 UNIX, the machine provided a familiar software environment for scientific and engineering workloads. Its inclusion in the TOP500 highlighted the feasibility of building competitive supercomputers with Intel hardware, influencing subsequent designs and encouraging broader adoption of Intel processors in large‑scale computing. The performance figures—though modest by today’s standards—were notable for the early 1990s and contributed to the evolution of parallel processing architectures that underpin modern high‑performance systems.

## Notable For  
- **TOP500 Listing:** Assigned system ID 283, confirming its status among the world’s fastest computers at the time.  
- **Intel Supercomputing Milestone:** One of Intel’s earliest supercomputers, demonstrating the company’s capability beyond consumer CPUs.  
- **Multi‑OS Compatibility:** Simultaneously supported OSF/1 and Tru64 UNIX, offering flexibility for diverse scientific applications.  
- **56‑Core Architecture:** Utilized a relatively high core count for its era, enabling parallel computation.  
- **Performance Progression:** Documented performance improvements from 1993 to 1994, reflecting iterative optimization.

## Body  

### Overview  
XP/S4 is classified as a **supercomputer** and was built by **Intel**. It appears in the **TOP500** ranking under the identifier **283**. The system was operational in the early 1990s, with performance measurements recorded in 1993 and 1994.

### Hardware  
- **Processor cores:** 56 cores.  
- **Manufacturer:** Intel, a leading semiconductor and hardware provider.  
- **Design focus:** High‑throughput parallel processing for scientific and engineering tasks.

### Software Environment  
- **Primary OS:** **OSF/1**, a Unix variant created by the Open Software Foundation.  
- **Additional OS support:** **Tru64 UNIX**, an operating system originally developed by Digital Equipment Corporation and later owned by Hewlett‑Packard.  

Both operating systems provided a Unix‑compatible environment, facilitating the porting of existing scientific codes.

### Performance Metrics  
| Date (YYYY‑MM‑DD) | Rmax (gigaflops) | Rpeak (gigaflops) |
|-------------------|-----------------|-------------------|
| 1993‑06‑01        | 1.5             | 2.8               |
| 1993‑11‑01        | 1.5             | 2.8               |
| 1994‑06‑01        | 1.75            | 2.8               |
| 1994‑11‑01        | 1.75            | 2.8               |

- **Rmax** denotes the highest measured performance during benchmark runs.  
- **Rpeak** represents the theoretical maximum based on hardware specifications.  

### Historical Context  
During the early 1990s, the supercomputing landscape was dominated by vector machines and emerging parallel architectures. XP/S4’s inclusion in the TOP500 list signaled Intel’s growing role in this domain. Its use of Unix‑based operating systems aligned with the broader scientific community’s preference for open, portable software environments.

### Legacy  
XP/S4 set a precedent for later Intel supercomputers, influencing design choices such as multi‑core scaling and Unix compatibility. The system’s documented performance trajectory demonstrates early efforts to refine parallel efficiency, a principle that continues to drive modern high‑performance computing.