Digital PDP15 Price List, April, 1970

In Short

This document is a technical price list and configuration guide for the Digital Equipment Corporation’s PDP-15 computer system, dated April 1970. It acts as a comprehensive inventory of the hardware components required to build everything from a basic entry-level machine to a sophisticated, disk-oriented background/foreground system. By categorizing processors, memory modules, I/O devices, and display hardware, it captures the modular ethos of mid-century engineering. It stands today as a vital primary source for understanding the physical reality, economic scale, and logistical complexity of early industrial computing.

The Story

The narrative of this document begins with the basic building block: the PDP-15/10. It represents the entry point for the user, a system centered on 4,096 words of 18-bit core memory and a humble KSR-33 Teletype. From this modest foundation, the text methodically unfolds an expansive hierarchy of technological growth. The story is one of iterative expansion, where the user is invited to ascend through a series of "systems"—the 15/20, 15/30, and finally the 15/40. Each step upward introduces greater complexity, adding features like the Extended Arithmetic Element, real-time clocks, and memory protection, until the machine evolves from a simple tool into a high-capacity, disk-oriented powerhouse.

As the systems grow more capable, the document shifts focus from the central processor to the periphery. The middle chapters detail the vast constellation of hardware required to make the machine useful to a human operator. We see the introduction of mass storage, specifically the transition from DECtape transports to the high-capacity RF15 DECdisk drives. The narrative then delves into the world of input and output, presenting a dizzying array of card readers, line printers, and plotters. It is a story of connectivity, where the user must navigate the fine print of bus converters and interface cables to ensure that these disparate pieces of hardware can communicate with the core processor.

The final act of the text moves away from the machine itself and into the infrastructure of global commerce. It catalogs the specific needs of the operator: supplies kits containing certified tapes, teletype ribbons, and fan-fold paper, ensuring the machine remains operational over time. The document concludes by mapping the reach of the manufacturer, providing a exhaustive directory of regional offices spanning the United States, Canada, Europe, and Australia. This final section transforms the technical guide into a map of an industrial empire, illustrating how a piece of hardware in 1970 was supported by a sprawling, international network of sales and service hubs. The arc is complete: the reader moves from the internal logic of a 18-bit core memory module to the physical reality of a regional office in Geneva or Sydney, demonstrating how one computer system was deeply embedded in the logistical fabric of the late twentieth century.

How It Unfolds

The foundation of the system The text opens by establishing the baseline configuration, the PDP-15/10, detailing the core memory requirements and the specific teletype models necessary for operation. It immediately sets the tone by linking financial cost to specific hardware capabilities.

The ladder of complexity The middle section organizes the machine into distinct system tiers, showing how the addition of specific components like the KA15 Automatic Priority Interrupt or the KM15 Memory Protection transforms a basic unit into a high-level background/foreground system. This creates a clear, logical progression of power and cost.

The peripheral ecosystem The focus then turns to the external world, cataloging mass storage, display devices, and input methods. It highlights the granular nature of these components, noting which peripherals require specific controllers or bus converters to function.

The maintenance and global reach The final movement covers the supplies needed to sustain the hardware, such as certified DECtape and specialized paper. It closes with a comprehensive list of corporate locations, grounding the abstract technical specifications in a wide-reaching, physical service network.

The People

While this is a technical document, the "people" involved are the architects, the procurement officers, and the system engineers who stood before these machines. The architects are represented by the designers of the DEC system, who value modularity above all else; they want to provide a machine that can be everything from a research laboratory workstation to a data processing hub.

The procurement officers are the silent protagonists, the ones tasked with balancing the $15,600 price of a base system against the $91,000 cost of a fully configured 15/40. They must navigate the "Notes" section, which acts as a series of constraints—for instance, the rule that only one controller may be attached to a system—forcing these decision-makers to choose between competing hardware priorities.

Finally, the system engineers are the ones who must bridge the gap between the components and the reality of the machine. They are the ones who decipher the complex table of bus cables, deciding whether they need a 7-foot or a 100-foot connection to make the system work. Each user ends up different based on their configuration; the researcher with the VP15CL oscilloscope display gains a visual, interactive experience, while the office administrator with the card reader and line printer is transformed into a high-volume data processor.

In Its Own Voice

=PDP-15/10: BASIC SYSTEM= 4,096 18-bit, 800-ns core memory $15,600 $150.00 Yes

This line establishes the entry-level price and fundamental hardware specs for the baseline model.

NOTE: Only one of each peripheral controller may be attached to a PDP-15 system.

This note illustrates the strict architectural limitations that engineers had to navigate when expanding their machines.

=SUPPLIES KITS= Contains 18 Certified DECtapes, 1 DECtape carrying case, 250 blue DECtape ribbons...

This inventory highlights the physical, consumable nature of early digital data storage.

What It's Really About

At its core, this book is about the commodification of logical complexity. It argues that computing power is not a monolithic object but a modular assembly that can be tuned to the specific needs of an institution. It explores the tension between standardization—the reliance on the PDP-15 bus and specific controller protocols—and customization, where the user can mix and match storage, input, and display technologies. The book asks questions about the nature of capacity: how much memory is "enough," and how the architecture of the system dictates the limits of what a computer can achieve. It frames the machine as a malleable, growing organism rather than a static product, reflecting a moment when the boundaries of the digital world were being physically bolted together, one component at a time.

Why Read It Today

Reading this today is an act of archaeological reconstruction. It offers a visceral sense of what it felt like to encounter a computer in 1970—a time when digital power was measured in 800-nanosecond core memory, and "display devices" were essentially oscilloscopes. A reader will love this if they have an interest in the history of technology or an appreciation for the precision of vintage industrial documentation. The experience is meditative and stark; the text is stripped of all modern marketing fluff, leaving only the clean lines of prices, model numbers, and technical prerequisites.

It can be difficult, as it requires a reader to mentally assemble the machine from a list of parts, but the reward is a clear-eyed look at a period before the "black box" era of computing. The period attitudes are evident in the emphasis on manual service and the requirement for specific, tactile media like paper tape and teletype ribbons. What stays with the reader is the sheer tangibility of the system—the weight of the cabinets, the length of the cables, and the clear, logical path from a base unit to a specialized, powerful machine. It is a stark reminder that the digital world was once an environment of copper, steel, and mechanical switches.