Xerox Alto Is Rebuilt and Reconnected by the Living Computer Museum

Paul G. Allen on 2016-07-19

It’s one thing to read about a true breakthrough, something else to see it in action

The Xerox Alto in the restoration workshop at the Living Computer Museum in Seattle.

About 35 years ago in an office at Xerox PARC, I watched a demonstration of a new research computer called Alto that stunned me. “Wow,” I thought. “This is going to change everything.”

And it did. The Alto’s many innovative features and capabilities — which Microsoft embraced as it developed Windows and subsequent software — would soon drive the widespread adoption of the personal computer. Just a few of the Alto’s firsts included:

A restored Xerox Alto at the Living Computer Museum running Maze War.

The Alto computer itself didn’t reach a wide audience — Xerox failed to recognize its potential and produced only a limited number for themselves, government and universities. But the machine quickly inspired people like me, Bill Gates, Steve Jobs and others to create the software and hardware that made GUI central to the computing experience, which soon put the power of computers into the hands of millions of people.

In recognition of the Alto’s historic impact, my team at The Living Computer Museum has restored two of the world’s surviving machines to full working order. And, since Ethernet networking was one of the Alto’s innovations, the LCM team has created the ability for the Altos to talk to modern computers by developing a 3-megabit bridge. As far as we know, this is the first time that Altos have been able to communicate with modern PCs.

The inside of a 3-megabit Ethernet transceiver that connects the Alto to a coaxial Ethernet cable.

My team and I aren’t the only ones working to keep the Alto’s legacy alive. During our restoration effort, we learned about a handful of other working Altos, including the machine that Ken Shirriff has begun to restore for Y Combinator. With this in mind, we’ll be releasing an Internet PUP gateway to allow Alto networks around the world to talk to each other, which will expose more enthusiasts to these historic machines and hopefully prompt still more renovations.

The ContrAlto emulator software in action at the Living Computer Museum

While the restored Altos at the Living Computer Museum give the public a rare opportunity to see and use the actual machines, we wanted to give even more people access to the Alto experience. That’s why the team has also developed a complete Alto emulator.

ContrAlto is a software program that simulates the original Alto hardware and allows original Alto software to be run on modern PCs. ContrAlto simulates the Alto at the microcode level, providing a very accurate simulation of the original computer. Even the original Ethernet networking is simulated, so multiple Alto emulators — and real Altos! — can share files, send e-mail and play vintage Alto games. I’ve had the chance to use both the restored Alto and the emulator, and the experience reminded me of how much that breakthrough computer enabled me to see the future and translate that possibility into reality.

ContrAlto in action as Living Computer Museum’s team tests out the emulator by playing Maze War.

Given what the Alto’s breakthroughs ultimately enabled, as well the machine’s profound impact on my career, it’s been a lot of fun to revisit and revive these historic computers. I hope people will enjoy playing with them as much as I do, and always keep pressing ahead to invent a better future.

ContrAlto: A Xerox Alto Emulator - Living Computer Museum Download the ContrAlto software for