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Restoring YC's Xerox Alto: how our boot disk was trashed with random data

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Re: Restoring YC's Xerox Alto: how our boot disk was trashed with random data

#21
Out of curiosity: what would it take to turn that disk back into a working boot disk? I can only imagine how difficult it must be to find an Alto _with two disk drives_ these days to dub a boot disk onto your scrubbed one.

Does the Alto have any sort of recovery environment? e.g: boot from the (3Mbit?) Ethernet, or boot from a floppy/tape, etc. that would aid in such a task?

Re: Restoring YC's Xerox Alto: how our boot disk was trashed with random data

#22
post #21

Out of curiosity: what would it take to turn that disk back into a working boot disk? I can only imagine how difficult it must be to find an Alto _with two disk drives_ these days to dub a boot disk onto your scrubbed one. Does the Alto have any sort of recovery environment? e.g: boot from the (3Mbit?) Ethernet, or boot from a floppy/tape, etc. that would aid in such a task?

The easiest thing would be to boot the Alto off a good disk, then swap the disks and write a good boot environment to the bad disk. (You can switch disks while the system is running.)

One of the guys working on the restoration (Carl) is building a FPGA-based disk emulator, which we could use to re-write the bad disk (as well as read and archive disks).

The Alto supports network boot over Ethernet; I'm working on a BeagleBone-based Ethernet emulator/gateway so that's another option. (The Alto's 3 Mbit Ethernet isn't compatible with anything modern, so I can't just plug an Ethernet cable into it.)

Re: Restoring YC's Xerox Alto: how our boot disk was trashed with random data

#23

The shift-xor "random" number generator described actually has an interesting property. The algorithm looks like this: 1. If the value is 0, output the magic number. 2. If the value has only its high bit set, output 0. 3. Otherwise, shift the value to the left 4. if there was an overflow (the high bit was 1 before the shift), xor the value by a magic constant. For certain values of the magic constant, this has the pr…

And with 077213 and 012345 octal that is what happens. That's why the distribution was so uniform when Ken checked.

Re: Restoring YC's Xerox Alto: how our boot disk was trashed with random data

#24
post #9

I know it's not really relevant to the repair work, but I jumped back to the first article, at http://www.righto.com/2016/06/y-combinators-xerox-alto-resto... . It says > The biggest impact of the Alto was in 1979 when Steve Jobs famously toured Xerox and saw the Alto and other machines. When Jobs saw the advanced graphics of the Alto and Star, he was inspired to base the user interfaces of the Lisa and Macintosh sys…

You should browse around folklore.org and look at the posts about the early Macintosh:

http://www.folklore.org/StoryView.py?project=Macintosh&story...

The Lisa and Macintosh projects interfaces pre-Xerox visit were remarkably different from post-visit. The Macintosh pre-early-1980-Xerox-visit was based around soft keys. Yes it had a bitmapped graphical display, but it was not a mouse based user interface as we know it, it was more like what Raskin did later with the Canon Cat.

The office desktop with icons interface that shipped on the Lisa is very clearly influenced by the Xerox Star office system more than it is by Smalltalk. And the Mac copied the Lisa.

Re: Restoring YC's Xerox Alto: how our boot disk was trashed with random data

#26
post #22
post #21

Out of curiosity: what would it take to turn that disk back into a working boot disk? I can only imagine how difficult it must be to find an Alto _with two disk drives_ these days to dub a boot disk onto your scrubbed one. Does the Alto have any sort of recovery environment? e.g: boot from the (3Mbit?) Ethernet, or boot from a floppy/tape, etc. that would aid in such a task?

The easiest thing would be to boot the Alto off a good disk, then swap the disks and write a good boot environment to the bad disk. (You can switch disks while the system is running.) One of the guys working on the restoration (Carl) is building a FPGA-based disk emulator, which we could use to re-write the bad disk (as well as read and archive disks). The Alto supports network boot over Ethernet; I'm working on a Be…

> You can switch disks while the system is running

Is that something you can do at any time, or only at the "home" screen when no apps are running?

Re: Restoring YC's Xerox Alto: how our boot disk was trashed with random data

#27
post #13

Earlier quoted context omitted.

Chapter 23 of "Dealers of Lightning" points out that everyone describes the Steve Jobs visit(s) in contradictory ways. "No anecdote from PARC's history is burdened by so much contradictory testimony. PARC engineers disagree about who delivered what portions of the demonstration; on how many demos there were and when they took place; whether Jobs and his people saw an Alto or a Dorado..." I recommend "Dealers of Light…

No surprise that Jobs would fixate on the UI thing. He never struck me as a techie, but someone that got into tech because it was easy to mesmerize people with. The UI was a perfect tool for that.

You're saying it like GUIs are just a trick, an illusion...

Re: Restoring YC's Xerox Alto: how our boot disk was trashed with random data

#28
post #5
post #2

I love these posts. I don't properly understand the majority of what's being done, but a step by step of somebody solving a difficult problem in a space I know nothing about is so fascinating.

I love these posts too, but man is it a pain to read on mobile. Quit hijacking my input! Edit: I know I can use the readability mode, but I don't like being essentially forced to do so.

Looked fine on iPhone. What phone do you have?

Re: Restoring YC's Xerox Alto: how our boot disk was trashed with random data

#29
post #22

Earlier quoted context omitted.

The easiest thing would be to boot the Alto off a good disk, then swap the disks and write a good boot environment to the bad disk. (You can switch disks while the system is running.) One of the guys working on the restoration (Carl) is building a FPGA-based disk emulator, which we could use to re-write the bad disk (as well as read and archive disks). The Alto supports network boot over Ethernet; I'm working on a Be…

> You can switch disks while the system is running Is that something you can do at any time, or only at the "home" screen when no apps are running?

I think you can switch disks pretty much any time. The Alto doesn't swap to disk so the disk is only being used when you're loading a program or loading/saving a file. As far as how it's used, think of the Alto's disk more like a floppy drive than a hard drive. (Although since it takes a minute for the disk to spin up to speed, you don't want to switch disks too often.)

Re: Restoring YC's Xerox Alto: how our boot disk was trashed with random data

#30
post #20
post #13

Earlier quoted context omitted.

Chapter 23 of "Dealers of Lightning" points out that everyone describes the Steve Jobs visit(s) in contradictory ways. "No anecdote from PARC's history is burdened by so much contradictory testimony. PARC engineers disagree about who delivered what portions of the demonstration; on how many demos there were and when they took place; whether Jobs and his people saw an Alto or a Dorado..." I recommend "Dealers of Light…

Your comment reminded me of this interview [1] with Steve Jobs: "And they showed me really three things, but I was so blinded by the first one that I didn't even really see the other two. One of the things they showed me was Object Oriented Programming. They showed me that, but I didn't even see that. The other one they showed me was really a networked computer system. They had over a hundred Alto computers, all netw…

>Now remember, it was very flawed; what we saw was incomplete, they'd done a bunch of things wrong, but we didn't know that at the time.

I find it amusing how Steve Jobs crams three negs into one sentence.

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