This sounds impressive. Was it common for machines of that era to be able to boot from the network?
Also, aren't those some awfully long wires to make high-frequency measurements with an oscilloscope? Some of that ringing and overshoot in the clock signals might not actually be in the circuit that is being probed, but caused by the long leads.
One entertaining thing about Alto boot: you could select a different boot address (i.e. boot something different) by pressing various keys at boot time. Each key controlled a different bit, so you would press many keys at once. This was called "nose boot" since you might need to use your nose to press a key if you ran out of fingers.
The Alto clock is 5.88 MHz, so the signals aren't as high frequency as modern computers. We could probably get crisper signals with better probing, but since we just want to see the signals, the quality isn't too important.
I'd really recommend a Saleae Logic here to scope out your digital lines. You probably don't need the high-level protocol decoding at this point, but for capturing longer blocks of data with a great interface you can't beat this tool.
Thanks for the detailed articles, it is much appreciated!
What network? This was the first machine to have a local area network.
A full Alto network included workstations, a file server, a laser printer, and a gateway to other Xerox networks using Parc Universal Protocol over 3Mb/s Ethernet. They had a complete all-Xerox vision.
There were other networking implementations being developed around the same time as Ethernet (1973-74), for example:
- DECnet (1974): https://en.wikipedia.org/wiki/DECnet
- Token Ring networks (1974): https://en.wikipedia.org/wiki/Token_ring
The earliest reference I could find to a LAN was the "Octopus" network from 1970, which predates Ethernet:
Since this was a big, but slow, storage device, it had to be front-ended by a computer with disks, and made accessible to other computers. That's most of what Octopus did. It wasn't peer to peer, like Ethernet.
A PhotoStore "chip" https://www.youtube.com/watch?v=4-Jvd7lOjWA
The Alto becomes more impressive the more time one spends thinking about it, you have to actively compare it to the state of the art back then to see the innovations that we now take for granted.
Making the technology cost-effective took a while. Around 1980, the UNIX workstations started to appear. Those tended to run around $20K each. By 1982 or so, you could have workstations, file servers, and printers from several vendors. Apollo, Three Rivers, and later Sun got into the business. The big problem was that, in the UNIX command-line tradition, none of these companies could do a decent GUI. (Most windows were either a terminal or an editor. Or a clock. Everybody had a GUI clock, with animated clock hands.) There was very little commercial software. One of the best pieces of software of the era was Interleaf, which was a very good WYSIWYG document editor, sort of like Microsoft Word. But it was sold as a $60,000 system including a workstation and a laser printer. There was no software mass market yet.
So all the key hardware was available years before the Macintosh came out. It just cost too much. And nobody had a good GUI.
Except Xerox, with the Xerox Star, 1981. But they had a different corporate vision - a dedicated system for word processing and document handling. The idea of tens of millions of people having to learn about the internals of complicated computers, just to do ordinary office tasks, was scary. How could Xerox support that? Xerox was into support; copiers were rented and service was part of the rental. So the Xerox system was a closed environment. Users could only run the Xerox-provided applications.
What Xerox didn't envision was a society in which computer literacy was widespread. Society backed into that, via the IBM PC, DOS, and open systems.
For others that have been following his work (and talks), it doesn't really contain much new stuff, but the context of a talk to an audience of programmers brings out some different contexts. He touches on the the fact that they didn't "just" spend extra money to prototype the dynabook in the form of the Alto - but they built 2000 machines - and part of that is of course so they could invite (among others) whole classes of school children to come and play with the tech.
When I mix the information written there with my own experience using Smalltalk and Oberon, it is quite eye opening in terms of overall experience.
Nowadays I think Mac OS and Windows are the only two major environments whose experience comes close to it.
And imagine a fairly powerful OS which was so simple at heart that you could read the entire source and understand it. (Lyon's samizdat book helped, too.)
For those of us studying systems at the time, it was magical.
His paper is at http://history-computer.com/Library/Kay72.pdf
And the Lisa could talk something they called AppleNet.
(Yes, CHAOSnet was a copy of the ideas from PARC's Ethernet, but IIRC (I was around) it was very close to the same time period.)
Really curious what they find out about the disk, nothing at all coming over the interface sounds like a big (and usually simple) issue, like card in the wrong slot or cable plugged in backwards or to the wrong connector.
To clarify the disk issue, we're seeing sector pulses coming from the disk drive, so the drive and cabling is working. The Alto isn't sending any read requests to the drive, so it seems most likely that the microcode isn't seeing any disk request block in memory.
A lot of things need to work correctly to get the request block into RAM. So it could be a problem with a chip on the ALU board, a bad memory chip, something wrong on the disk interface card, a corrupted bit somewhere, or anything. With the logic analyzer, we should be able to see at what point in the microcode things go wrong. The nice thing about the Alto is because it's all TTL chips, it's straightforward to see what's happening.
The whole museum is great and I highly recommend it to anyone who finds themselves in Seattle. There's something intensely satisfying about writing, compiling, and running Hello World on a teletype (paper roll!) hooked up to a PDP-7.
i have no experience with altos but i have been wondering -- on day one of the restore, it was noted the alto in question had some modifications from stock issue, could the booting issues be related to the microcode or wiring changes necessary to support those modifications? is it trying to boot off of the now missing trident drive?
 from http://www.righto.com/2016/06/restoring-y-combinators-xerox-...
"I suspect that the Y Combinator Alto originally had both a Trident drive and a Diablo drive (as well as four Orbit boards to drive a laser printer)"
It seems like the Trident drive shouldn't be causing us any problems, but it's possible there's a wiring change or different PROMs. I guess we'll find out...