DEC's 40 years of innovation

Ken Olsen, founder of Digital Equipment Corporation, died on 6 February, aged 84. In the 40 years between DEC's foundation and its purchase by Compaq, the company brought computing to millions of people through excellence in engineering and vision in design. It also created the first hacker culture — not in the security sense, but by letting people get the intimate access to technology that inspires creativity, lateral thinking and downright cleverness.

This gallery shows just some of the highlights of the company's time at the heart of IT. A full description of how DEC changed the world would take an encyclopaedia, but we hope you enjoy this small selection of DEC's landmarks, presented in memory of Olsen.

The Digital Equipment Corporation's first products were a range of pre-packaged logic circuits, the Digital Laboratory Modules. Each was similar in function to the sort of logic chips that computer designers used in the 1970s, but was made out of individual transistors, resistors and so on, and was consequently much larger.

The user typically bought a rack and a range of modules, wiring them together to perform a specific digital logic function. Potentially, this could even be a simple computer, although most people created custom circuits for control or measuring of laboratory or production processes. A manual for the range is available here (PDF).

DEC's first computer saw daylight in 1960 and was built out of the company's own logic modules, repackaged so they shared a bus at the back of their case instead of being patched by wire at the front.

Running at 5MHz and coming with a standard 9KB of memory, the machine was called the PDP-1, or Programmable Data Processor — a deliberate attempt to avoid the esoteric, expensive connotations of the word 'computer'. Costing the rough equivalent of £500,000 in 2011, 53 were made, of which there are three known survivors.

The computer was in fact relatively cheap, small and easy to install, as it needed no air conditioning.

Although the base model only had switches, lights and a modified electric typewriter for input and display, peripherals included the first commercially available graphics display — which inspired the first recognisable computer game, 1962's Spacewar!. A Java emulation of a PDP-1 running Spacewar! can be run here, and the PDP-1 manual is available here.

The PDP-11 is widely regarded as one of the key computers of the 20th century. Introduced in 1970 and available in a bewildering number of models and configurations, variants were in production until 1990.

Most of the pioneering work on Unix and the C language was done on PDP-11s, so the heritage of the design continues through Linux into the most modern mobile phones. The hardware also pioneered the practical application of many modern concepts, including orthogonal instruction sets, memory-mapped peripherals, and a bewildering array of options and ill-considered cost reductions.

Like almost all of DEC's minicomputers, the design ended its days in a variety of custom processors that used modern techniques to reduce a filing cabinet of silicon to a single chip.

For many programmers in the 70s and early 80s, the face of the computer was the DEC VT-52.

Its antique looks today belie its startling modernity at the time, which include such innovations as lower-case characters and text that could be scrolled up and down the screen. This was possible because the VT-52 was a smart terminal, containing a rudimentary computer of its own: it meant that crude WYSIWYG text editing became possible, and computerised typesetting began the slow march to dominance.

One variant, the VT78, had a complete single-chip PDP-8 built in with word-processing software and was thus a very early stand-alone office information appliance.

The VT-52 was followed by the even more iconic VT-100 and the positively elegant VT-220 — terminal types that live on in modern operating systems as modes in terminal emulators, and in the hearts of programmers as the early Bentleys of the interactive age.

1977's VAX 11/780 is seen as the high point in DEC's engineering and commercial history, although its raw specifications — 5MHz clock, 8MB maximum RAM — aren't that different to those of PCs that came just 10 years later. However, it achieved actual performance that belies those figures, supporting 30 or 40 users with ease.

VAX stands for 'Virtual Address eXtension', as the computer used virtual memory and a very efficient I/O system to behave like a much larger system. The actual performance was around one million instructions a second, making one VAX MIPS an industry standard benchmark metric.

The VAX range, which was in production until the early 2000s, was hugely influential in both chip architecture and software design. On the later models, which used a single-chip processor, DEC's engineers took to engraving messages in Russian on the silicon die, to entertain their counterparts in Russia who were busy reverse engineering just about everything DEC did.

If the VAX 11/780 was the high-water mark of DEC's dominance, the Rainbow 100 was a bad omen for the future. An idiosyncratic design that married a Z80 chip with an 8088, it managed to be compatible with very little and annoy users very much.

Taken as a stand-alone computer, the hardware was built to DEC's usual high standards; in the PC market, it was a bad fit. The user couldn't format floppy disks, which had to be bought pre-formatted from DEC. It wasn't PC compatible, so it couldn't run much software. It had an odd keyboard layout. It cost $3,000.

There are many signs that DEC itself wasn't too keen on the Rainbow, as little marketing was done and the sales teams got more money for less work by selling minicomputers. Plus, it was mostly built around technologies that DEC hadn't invented, which, in a fiercely proud engineering company, rarely endears a product.

The result, in the end, was that DEC missed the microcomputer revolution and was buried, much as most of the mainframe manufacturers had dismissed minicomputers 20 years before.

In 1992, DEC had one final burst of genius — the DEC Alpha processor.

Although the company had had considerable success with the single-chip versions of its minicomputers, the architectural limitations had made them obsolete in any format. The Alpha chip was designed on RISC principles and was intended to support a thousandfold increase in performance over its projected 25-year lifespan.

There is evidence that the Alpha would have succeeded. The first versions, the 21064 line, produced unparalleled performance for the CMOS process on which they were built, foreshadowing Intel's later success in pushing that technology. Later versions introduced on-chip secondary caches, high-speed out-of-order execution and on-chip memory controllers. They would have supported simultaneous multi-threading, had the design not been cancelled after Compaq's 1998 purchase of DEC.

Although the Alpha continued as a server chip for some time, software and hardware support dropped off and it was finally killed when Intel persuaded its customers that the Itanium was going to be the muscle chip of choice.

One of DEC's last pieces of innovation was the StrongARM, a curious combination of ARM's low-power processor architecture and elements of the Alpha's high-performance design. The chimera was surprisingly successful, finding its way into PDAs and set-top boxes and helping establish the ARM architecture in a number of new — and subsequently very important — niches.

The design proved more important as a bargaining chip than a processor chip, as it was passed to Intel as part of a complex deal to settle an intellectual-property dispute. Intel developed the design into the XScale processor, which was in turn sold to Marvell Technology Group in 2006, prior to Intel's announcement of its Atom low-power x86 processor.

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