Digibarn Xerox Alto Resurrected! (Patreon)

You might remember the episodes on the Digibarn Alto ( https://youtube.com/playlist?list=PL-_93BVApb59ameMVQhOAzeRcCpS6PCiG ).  In the picture below from the 2017 video, owner Bruce Damer and friend Lucca bring the  Digibarn Alto to my lab.

This was truly a barn find. It had been "inhabited" by barn critters, and we soon discovered that every single part of it was bad: each one of the four power supplies, the display, the disk, and every single board. It was actually never a functioning Alto. It was made of a stack of dead parts amassed by former Alto maintenance technician Ron Cude. It had missing boards, missing cables, an incomplete cabinet with no slide rails and broken casters. Moreover, the monitor that came with it could never have been connected to an Alto, as it was from a Dolphin or some later machine and used a different protocol and cable. 

We cleaned it all from the nuts, pee and poop, repaired the supplies which had tons of bad components, made an adapter for the monitor, repaired it, made new cables, added the missing cards, and tried to boot it up, which of course failed. At that point we realized that the project was going to take much more than we could take on at the time. 

So over it went to Josh Dersch, another restorer extraordinaire from the former Living Computer Museum (LCM) in Seattle. Josh had famously written the ContrAlto emulator which we used extensively, and volunteered to continue the restoration. Below is a picture of Josh at VCF 2017,  where he was networking his ContrAlto emulator (which you can see running in the background) with our real Alto, so we could play Maze Wars. 

Josh has a working Alto in his extensive collection, so he took each of the Digibarn boards, one at a time, put them in his Alto, and fixed them until they would boot in his Alto. He told me he had to replace more than 30 dead TTL ICs! You can get a sense of Josh's collection and skill by reading his blog here:

http://rottedbits.blogspot.com/2020/06/at-home-with-josh-part-1.html

Finally, last October, the boards repaired by Josh were put back in the Digibarn Alto. The Alto still had no working disk to boot from. But Ken had donated one of his Alto network emulators contraptions, which can be used to net boot the Alto. Josh tried to boot the Alto off Ken's emulator, but since we had returned the monitor in its Dolphin configuration, they could not connect it and see if anything happened besides a little blinky light on Ken's emulator. Also one of the power supplies failed again, so they called it a day. 

Last Thursday, Ken, Carl and I went on an expedition to the Digibarn for another boot attempt. The Digibarn is hidden in a remote corner of the Santa Cruz mountains, and had survived the California fires last summer by a mere mile and a half.  

That was my first look ever at Bruce Damer's extensive collection of old computers and related artifacts. Who else has a Cray-1 in his barn?

The Alto was patiently waiting in the last of many rooms. We realized that the failed supply was the +15V for the disk drive, which was not working anyhow, so that was not a concern, we could net boot without it. We re-modified the Dolphin monitor with an adapter designed by Ken so it could be connected to the Alto. But when we tried to test it with our special Alto monitor tester (a gift to us by the LCM), nothing came up. Turned out, our tester had failed! 

We then decided, in Wehrner Von Braun's style, to go for a full up test. We connected the monitor, Ken's network emulator, and off we went. The monitor lit up, uniformly white. After we finally remembered the odd keyboard combination for net booting, a blue light on Ken's Beaglebone emulator blinked, a cursor appeared on the screen, and a minute later, the Alto had booted!

We connected the mouse and the chord set, which I had previously restored, and everything pretty much worked. Here is the Alto displaying a picture of one of its designers, David Boggs, who was in the Ethernet pioneers video ( https://youtu.be/XhIohWr10kU ).

And here is delighted owner Bruce Damer, playing Trek on his new old machine!

So it took 4 years, but it's back! Or more exactly it's up, as it probably had never worked before. 

I'll try to assemble a video of the footage I got during the visit. Bruce's collection is amazing!

Marc