Xerox Sigma 9
Introduced in 1971
Xerox bought a series of computers originally intended for real-time computing from a company called Scientific Data Systems, with the goal of bootstrapping an office automation business. The Sigma series saw limited success and Xerox ultimately sold the business for a significant loss.

This computer was maintained by a private collector who originally used a Sigma to run a medical billing business. After he migrated his business over to more modern systems, he preserved several Sigmas and became a source of components and service for other users.

The first message sent over the Arpanet – the precursor of today's Internet – was sent from a Sigma 7 at UCLA to a Scientific Data Systems SDS 940 at the Stanford Research Institute.

DEC PDP-10: KL-10 (DECsystem-10)
Introduced in 1971
The KL-10 was the second in a line of 36-bit systems produced by DEC as successors to its groundbreaking, but poorly constructed, PDP-6. Like the PDP-6, the DECsystem-10 was designed to be a timesharing system, unlike IBM's computers which were batch processing platforms, or other companies' systems that were modified to support timesharing.

This system was originally installed as part of a dual-processor system, with shared memory for communication between the two processors.

DEC PDP-10: KL-10 (DECSYSTEM-20)
Introduced in 1974
The KL-10 was a new implementation of the PDP-10 architecture intended for high-end timesharing in datacenters. It was built using a fast but power-hungry technology called emitter-coupled logic (ECL), which was soon replaced by other methods of making logic components that used far less power but offered even higher speed.

Although the KL-10 was intended for the new TOPS-20 operating system, which provided more powerful tools for system developers, customers demanded that DEC provide a version of Tops-10 for the DECsystem-20 because of its more efficient use of resources. The improved quality of system services under TOPS-20 reduced the number of users it could support.

This computer was originally purchased by an accounting company, which subsequently sold it to Cisco Systems. Cisco sold it to its founders, who had created a new company called XKL to build smaller implementations of the PDP-10 architecture, and LCM later obtained the machine from XKL.

XKL TOAD-1 System
Introduced in 1995
TOAD stands for "Ten On A Desk." When DEC executives were deciding between the longstanding PDP-10 and the new VAX computer line, one argument was that the PDP-10 would not scale to the newly popular desktop size.

Some of the veterans of DEC's now discontinued Large Systems Group ultimately created this machine to demonstrate that the PDP-10 architecture could meet modern needs. But by the time it was available, the VAX and 32-bit workstations were satisfying the market formerly dominated by 36-bit PDP-10s.

The internals of the TOAD-1 live on in high-end network switches produced by XKL, Inc. of Redmond, Washington.

DEC PDP-10: KS-10 (DECSYSTEM-2020)
Introduced in 1979
The KS-10 was the last model in the PDP-10 family, built with new technologies to produce a "department-sized" computer that would serve a small office. By comparison, its predecessor, the KL-10, was intended for datacenters serving scores of simultaneous users. Microsoft purchased one as its first software development platform upon moving from Albuquerque to Bellevue, as the target personal computer systems were not powerful enough to support development work.

This machine served in the famous MIT Computer Science and Artificial Intelligence Laboratory as the last host for the Incompatible Timesharing System (ITS) environment devoted to artificial intelligence researchers.

DEC VAX-11/780-5
Introduced in 1982
The "VAX strategy" was developed by key DEC engineers in 1975 in response to high-end customers' needs for more address space to solve problems such as global weather modeling and complex geophysical research. This 32-bit computer incorporated virtual memory into its design, allowing large programs and data to be supported by a physical memory of feasible size and cost. The VMS operating system, developed at the same time, made use of this feature transparent to the application programmer.

This machine started out as an example of the original VAX-11/780. As was common practice, it was upgraded with a faster 11/785 processor, with details like a new faceplate to reflect its face lift.

Data General MV/8000
Introduced in 1980
Code-named "Eagle," this computer was an extension of the established Eclipse line from a 16-bit to a 32-bit word length. It was a response to DEC's VAX by Edson DeCastro, the man who left DEC to build computers his own way. As described in Tracy Kidder's book, The Soul of a New Machine, DeCastro had commissioned an elite group of engineers for the Fountainhead Project, which was to produce the VAX-killer. But it was a small group led by dynamo Tom West that successfully produced Eagle, taking big chances on new technology to produce a David-versus-Goliath win over the company's own status quo.

One especially unique feature of the Eagle is that 16-bit software may be run on it without modification. By comparison, its competitor, the VAX-11/780, could run 16-bit software only if a "compatibility bit" was set in its internal registers.