760927 DECsystem-10 Competitive Analysis

This confidential interoffice memorandum from Peter Christy to the Operations Committee, dated September 22, 1976, provides a competitive analysis of the DECsystem-10, primarily focusing on IBM's System/360 and System/370, with comparisons to PDP-11, VAX, and HP-3000.

The document highlights that while IBM's initial System/360 had weaknesses in interactive/real-time performance (which DEC's PDP-6, PDP-10, and DECsystem-10 exploited), IBM has since made "tremendous investments" in hardware and software development for the System/370. Key IBM advancements include:

• Virtual Memory: Eliminating architectural faults of the 360, making it more effective for interactive and distributed processing, and enabling features like VM/370 for virtual machines and rich time-sharing.
• Interactive Functionality: Significant development in applications like IMS, CICS, and TSO, and the introduction of systems like the 3705 communication processor and 3790 intelligent terminals.
• Technology Leadership: IBM's lead in semiconductor memory and disk storage (e.g., Winchester technology).

A crucial point is the "dramatic repricing" of the System/370 models 138 and 148 in June 1976. These models offered performance improvements with up to 50% price reductions (especially in central memory), making IBM highly competitive on price/performance. This aggressively lowered the entry price for data base and data communication systems, making time-sharing and using IBM systems for backup more attractive, and integrated peripherals, CPU, and software more effectively.

The analysis evaluates systems based on Architecture, Implementation, Software Design, Software Maturity, System Maturity, and Basic Technology.

• IBM's System/370 generally excels in maturity and fundamental technology.
• DEC's PDP-11 is praised for maturity, high volume, and extensive software but is limited by address space and Unibus architecture.
• The PDP-11/VAX has a mature architectural design but is an immature product with low initial software investment.
• The DECsystem-20 boasts elegant design and PDP-10 software compatibility but suffers from low product volume, limited DECsystem-20-specific software, and a small number of available peripherals.
• HP-3000 Series II has some maturity but is criticized for architectural compromises and primitive software lacking powerful paging.
• Virtual memory implementations are also compared, noting that IBM's 370 family has a more complete memory hierarchy (including fixed-head disk options) compared to some DEC and HP systems.

In summary, the document concludes that IBM's substantial investments in addressing its historical weaknesses, combined with its aggressive pricing strategy for the 370/138 and 370/148, significantly challenge competitors like DEC by offering increasingly powerful, integrated, and cost-effective solutions for interactive and distributed applications.