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Comment by fit2rule | Hacker News Reader

This is a wonderful project, and definitely very interesting .. although the careful, snail-like pace of restoration is frustrating, the results are going to be quite rewarding.

[spoilers]

Does anyone know - does the Alto need to be booted from disk, or does it have a PROM loader, or some such thing as onboard firmware to do the boot loading - like, is the problem possibly that there is "no OS" on the disk, and they have to work out how to put it on there, or is this not booting due to some other logic-level problem, i.e. something wrong with the boards?

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Looking at [1], it would seem they actually need a bootable drive. Knowing what's on the drive... well, that's another story.

Interestingly enough, the Alto could also boot from the network [2], but I guess it would just be easier to take a bootable drive and copy it to the drive. Even creating a whole disk emulator would probably be easier than netbooting an Alto these days. Bootable disk images do exist, as you can use them with the Salto emulator.

[1] http://www.righto.com/2016/06/restoring-y-combinators-xerox-... [2] http://history-computer.com/ModernComputer/Personal/Alto.htm...

Thanks for the info - very informative.

Seems to me that they might be better off doing a netboot at first, since this is the booting technique that requires fewer moving parts and less wear and tear on the disk drive .. but I wonder if they did netboot, would they have everything onboard that they need in order to format/configure the disk drive for disk booting, next? So many questions .. I guess I should spend some hours with the Salto simulator, which seems like a guaranteed enjoyable waste of time! :)

The problem is, what do you netboot from?

Netbooting a modern computer from another modern computer is somewhat easy, but with old computers it can be a nightmare. I tried to boot OS9 on a G3 iMac from a 2012 Intel MacBook, and despite days of work I couldn't do it.

Wouldn't it be that the Alto uses normally available standard netboot protocols that could be set up easily with a Linux box somewhere?

Given that we are talking about a computer from 1973, the chance that there is anything "standard" about the network boot is minimal...

Edit: well damn, a quick search bulled up a lovely PDF from textfiles.com.

http://textfiles.com/bitsavers/pdf/xerox/alto/AltoBootProto....

Cool! It seems most internet gateways contain a boot server, problem solved ;)

Seriously though, I would bet that, with enough knowledge & time, you might find everything you need to netboot an Alto here: http://xeroxalto.computerhistory.org/

/Ibis/AltoGateway/Servers/BootServer* looks promising

Yeah, still need to set up another computer on a ethernet (likely the good old thick coax kind with 75 ohm terminators) network that behave properly according to the pdf. Fun times...

BTW, if anyone wonders what pup stands for in that pdf:

https://en.wikipedia.org/wiki/PARC_Universal_Packet

The main problem with booting the Alto off Ethernet is that it uses 3 Mb/s Ethernet, which is incompatible with "modern" Ethernet hardware. We can't just plug an Ethernet cable into the back of the Alto. Back then, Ethernet used a "vampire tap" that clamped onto a coaxial cable with spikes that pierced the cable to make the connection. And you could only make connections at special spots on the cable (marked with black stripes) in order to avoid signal reflections. https://en.wikipedia.org/wiki/Vampire_tap

The Living Computer Museum in Seattle is building a 3 Mb Ethernet gateway, which potentially would allow network booting.

Glad i got into networking at the tail end of the thin-coax era...

10M thick Ethernet also had vampire taps and cable (about 1/2 inch diameter) with marks on it.

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