OSfOM

IBM's Pizza Box
In the early 1990s, IBM was riding the wave of its highly successful RISC System/6000 (RS/6000) line, a competitor to Sun Microsystems and HP in the UNIX workstation and server markets. To bring this powerful, proprietary architecture to a broader, budget-conscious audience, IBM introduced a series of entry-level machines. Among the most historically significant was the IBM 7011 Model 220, announced in January 1992.

The Rise of the POWER Single Chip (RSC)
What made the 7011-220 unique was its internal hardware, which signaled a major shift in IBM's RISC strategy.

• Processor: The Model 220 was one of the first systems to utilize the POWER Single Chip (PSC) processor, later formally known as the RISC Single Chip (RSC). Clocked at 33 MHz, the RSC was a streamlined, single-chip implementation of the formidable multi-chip POWER Architecture found in the larger, more expensive RS/6000 models. This integration was key to reducing manufacturing costs and cooling requirements while retaining binary compatibility.
• Architecture: It ran on the Micro Channel (MCA) bus. While MCA was proprietary and eventually lost the battle to the industry-standard PCI, it was technically superior at the time, offering better multi-master capabilities and data integrity—qualities IBM valued for its reliable server and workstation environments.

• Memory: The system utilized standard PS/2 memory SIMMs, but incorporated Error Checking and Correction (ECC) for high reliability, reflecting its professional market positioning. Memory could be expanded up to 64 MB.

   

Workstation or Server? Yes.
IBM positioned the 7011 Model 220 with dual purpose: it was sold as both a POWERstation (desktop workstation) and a POWERserver (network server).

• Workstation: Equipped with optional graphics adapters like the POWER Gt1 (and later upgradable to the Gt3/Gt4), the 220 served as a capable AIX workstation for software development, technical computing, and CAD/CAM, especially for users who didn't require high-end 3D graphics.
• Server: Its integrated SCSI and Ethernet controllers, along with the option for a 400 MB SCSI hard disk, allowed it to function perfectly as a small, reliable LAN-attached server for files, print services, or development teams. It could even run diskless in a centralized environment.

The Legacy of the Entry-Level
The IBM 7011 Model 220 may look unassuming, but its impact was significant:

• Lowered the Barrier to Entry: By streamlining the POWER architecture into the RSC, IBM could offer a true RS/6000 experience at a lower price, expanding the reach of AIX and the POWER platform.
• Paved the Way for PowerPC: The RSC was a direct ancestor to the collaborative PowerPC architecture (developed with Apple and Motorola). The success of chip integration in the 220 series demonstrated the viability of the single-chip RISC future.

• Enduring Reliability: Like most IBM machines of this era, the 7011-220 was built to last. Many units remained in service for over a decade, a testament to the stability of the hardware and the AIX operating system.

   

The IBM 7011 Model 220 ultimately proved that high-performance UNIX computing didn't require a refrigerator-sized cabinet. It established the "pizza box" as a legitimate form factor for serious professional work, cementing its place as a cornerstone in the history of the legendary RS/6000 family.