6 ms·

> If backspace is pressed on the keyboard, the Alto does a Ethernet boot This sounds impressive. Was it common for machines of that era to be able to boot from

> If backspace is pressed on the keyboard, the Alto does a Ethernet boot 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.

kens 10y ago
Ethernet was invented for the Alto, so it was the first machine to boot over Ethernet. (I don't know if any other machines did network boot earlier, using other networks.) 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.
- MrBuddyCasino 10y ago
  So ctrl+alt+del did have some precedent... Good luck with the restoration effort, tracing the instructions using a logic analyzer seems like a daunting prospect, especially with such an arcane instruction set. Thanks for the detailed articles, it is much appreciated!
- joezydeco 10y ago
  Man, doing that digital work with a scope can be painful at times. 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. https://www.saleae.com/ https://www.saleae.com/
  - kens 10y ago
    We (i.e. Marc) have a fancy HP logic analyzer with many, many input lines, so the plan is to use that next session. (Not that I have anything against the Saleae system.) I expect that once we can trace the executing code, we'll be able to figure out the problem quickly.
Animats 10y ago
"Was it common for machines of that era to be able to boot from the network?" 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.
- beachstartup 10y ago
  huh, i never knew that. sounds like apple copied more than just a user interface from xerox...
  - colejohnson66 10y ago
    Correct me if I'm wrong, but the original Macintosh didn't have networking support
    - protomyth 10y ago
      AppleTalk because of the serial chip they put in it.
      - ams6110 10y ago
        IIRC even the Apple II could do AppleTalk. Often used in classrooms to share a single hard drive among a dozen or more computers.
    - digi_owl 10y ago
      Well their original Xerox clone was the Lisa. The Macintosh was turned into a scaled down Lisa once Jobs was moved to that project. And the Lisa could talk something they called AppleNet. https://en.wikipedia.org/wiki/AppleTalk https://en.wikipedia.org/wiki/AppleTalk
- MrBuddyCasino 10y ago
  Ha, guess you're right. I was thinking about mainframe clients, but I guess in those days they didn't even have their own CPU? This was way before my time. 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.
13of40 10y ago
I remember reading that the original IBM PC motherboard got an Ack from the keyboard when it initialized, and if a particular bit was set in the ack character it would read boot code from the keyboard port. Apparently it was just for testing though....
cpr 10y ago
I think the AI Lab folks had LispM booting over CHAOSnet at MIT around the same time. (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.)

kens 10y ago

Ethernet was invented for the Alto, so it was the first machine to boot over Ethernet. (I don't know if any other machines did network boot earlier, using other networks.) 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.

MrBuddyCasino 10y ago
So ctrl+alt+del did have some precedent... Good luck with the restoration effort, tracing the instructions using a logic analyzer seems like a daunting prospect, especially with such an arcane instruction set. Thanks for the detailed articles, it is much appreciated!
joezydeco 10y ago
Man, doing that digital work with a scope can be painful at times. 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. https://www.saleae.com/ https://www.saleae.com/
- kens 10y ago
  We (i.e. Marc) have a fancy HP logic analyzer with many, many input lines, so the plan is to use that next session. (Not that I have anything against the Saleae system.) I expect that once we can trace the executing code, we'll be able to figure out the problem quickly.

Animats 10y ago

"Was it common for machines of that era to be able to boot from the network?" 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.

beachstartup 10y ago
huh, i never knew that. sounds like apple copied more than just a user interface from xerox...
- colejohnson66 10y ago
  Correct me if I'm wrong, but the original Macintosh didn't have networking support
  - protomyth 10y ago
    AppleTalk because of the serial chip they put in it.
    - ams6110 10y ago
      IIRC even the Apple II could do AppleTalk. Often used in classrooms to share a single hard drive among a dozen or more computers.
  - digi_owl 10y ago
    Well their original Xerox clone was the Lisa. The Macintosh was turned into a scaled down Lisa once Jobs was moved to that project. And the Lisa could talk something they called AppleNet. https://en.wikipedia.org/wiki/AppleTalk https://en.wikipedia.org/wiki/AppleTalk
MrBuddyCasino 10y ago
Ha, guess you're right. I was thinking about mainframe clients, but I guess in those days they didn't even have their own CPU? This was way before my time. 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.

13of40 10y ago

I remember reading that the original IBM PC motherboard got an Ack from the keyboard when it initialized, and if a particular bit was set in the ack character it would read boot code from the keyboard port. Apparently it was just for testing though....

cpr 10y ago

I think the AI Lab folks had LispM booting over CHAOSnet at MIT around the same time. (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.)