Fire-Breathing Dragon: the Story of the Dorado Computer

In 1979, three years after Alan Kay had wanted to throw away the Altos like Kleenex," the Dorado, a machine 10 times more powerful, finally saw the light of day.

It was supposed to be built by one of the development organizations because they were going to use it in some of their products," recalled Severo Ornstein, one of the designers of the Dorado and now chairman of Computer Professionals for Social Responsibility in Palo Alto. But they decided not to do that, so if our lab was going to have it, we were going to have to build it ourselves. We went through a long agonizing period in which none of us who were going to have to do the work really wanted to do it.

Taylor was running the lab by that time," Ornstein said. The whole thing was handled extremely dexterously. He never twisted anyone's arm really directly; he presided over it and kept order in the process, but he really allowed the lab to figure out that that was what it had to do. It was really a good thing, too, because it was very hard to bring the Dorado to life. A lot of blood was shed."

At first, Ornstein recalled, the designers made a false start by using a new circuit-board technology-so-called multiwire technology, in which individual wires are bonded to a board to make connections. But the Dorado boards were too complex for multiwire technology. When the first Dorado ran, there was a question in many people's minds whether there would ever be a second.

There Butler Lampson's faith was important," Ornstein said. He was the only one who believed that it could be produced in quantity.

In fact, even after the Dorado was redesigned using printed-circuit boards instead of multiwire and Dorados began to be built in quantity, they were still rare. We never had enough budget to populate the whole community with Dorados," recalled one former PARC manager. They dribbled out each year, so that in 1984 still not everybody had a Dorado."

Those who did were envied. I had a Dorado of my very own," said John Warnock. Chuck Geschke was a manager; he didn't get one."

In the early days...I got to take my Alto home. But the evolution of machines at Xerox went in the opposite direction from making it easy to take the stuff home.-Dan Ingalls

I got a crusty old Alto and a sheet of paper," Geschke said. The advent of the Dorado allowed researchers whose projects were too big for the Alto to make use of bit-mapped displays and all the other advantages of personal computers. We had tried to put Lisp on the Alto, and it was a disaster," recalled Teitelman. When we got the Dorado, we spent eight or nine months dis cussing what we would want to see in a programming environment that would combine the best of Mesa, Lisp, and Small talk." The result was Cedar, now commonly acknowledged to be one of the best programming environments anywhere.

Cedar put some of the good features of Lisp into Mesa, like garbage collection and run-time type-checking,'' said Mitchell of Acorn. Garbage collection is a process by which memory space that is no longer being used by a program can be reclaimed; run time type-checking allows a program to determine the types of its arguments-whether integers, character strings, or floating-point numbers-and choose the operations it performs on them accordingly.

Interlisp, the language Teitelman had nurtured for 15 years, also was transported to the Dorado, where it was the basis for a research effort that has now grown into the Intelligent Systems Laboratory at PARC.

PARC's Smalltalk group, who had gotten used to their Altos and then built the Notetaker, another small computer, had some trouble dealing with the Dorados.

In the early days, we had Smalltalk running on an Alto, and I got to take my Alto home," recalled Ingalls. But the evolution of machines at Xerox went in the opposite direction from making it easy to take the stuff home. The next machine, the Dolphin, was less transportable, and the Dorado is out of the question-it's a fire-breathing dragon."