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Restoring YC's Xerox Alto day 8: it boots

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Re: Restoring YC's Xerox Alto day 8: it boots

#71

Post by grecy »

rhardih wrote: post #18

This series is the best thing on HN in a long time. As a software engineer by trade, I feel like I've been missing out not learning more about electrical engineering. The level of knowledge and skill involved in this restoration is downright awe-inspiring.

At my University (Swinburne, Melbourne, Australia) I studied Software Engineering with a minor in Digital Electronics.

They said all along the goal wasn't for us to be as competent as the Electrical/Electronic Engineers, but to teach us their language and the basics so we could work together. It was great.

My degree is accredited by the Australian Institute of Engineers.

Re: Restoring YC's Xerox Alto day 8: it boots

#72

Post by linker3000 »

userbinator wrote: post #54
raldi wrote: post #17

I love that the first boot screenshot at https://lh3.googleusercontent.com/-JB4VOj7FgnU/V-lCHIADrsI/A... says: Date and Time Unknown Oh, you poor sweet computer, if we told you the answer, it would blow your little mind.

The PC had no RTC, so DOS would ask you the date and time every time you booted it: https://en.wikipedia.org/wiki/File:PC_DOS_1.10_screenshot.pn... ...and if you accepted the default, as many people at the time did, it would be 1980-01-01 00:00:00. DOS and the PC actually had no Y2K problem, storing the number of years since 1980 in a single byte --- which will overflow after 2235. It is notable that there is no year…

Yeah, yeah, get me the EGA card/memory update that includes the Dallas real time clock!

Re: Restoring YC's Xerox Alto day 8: it boots

#73

Post by linker3000 »

rhardih wrote: post #18

This series is the best thing on HN in a long time. As a software engineer by trade, I feel like I've been missing out not learning more about electrical engineering. The level of knowledge and skill involved in this restoration is downright awe-inspiring.

I could do vintage computer and electronics restoration all day...if it paid my bills!

Re: Restoring YC's Xerox Alto day 8: it boots

#74

Post by linker3000 »

makomk wrote: post #9
tiles wrote: post #6

This is an amazing milestone! I have to ask, why did we need a separate boot disk sent over instead of flashing the previous disk with the contents of a boot disk? I suppose swapping out parts is an expected part of restoration though.

They don't currently have any way of writing to the disk except using the Alto itself, which would require booting it first. Once they get it working they should be able to create their own boot disk.

That's a bit like my old soldering iron - the heating element was soldered to its wiring, so you needed a soldering iron to fix the soldering iron.

Re: Restoring YC's Xerox Alto day 8: it boots

#75

Post by ajdlinux »

grecy wrote: post #71
rhardih wrote: post #18

This series is the best thing on HN in a long time. As a software engineer by trade, I feel like I've been missing out not learning more about electrical engineering. The level of knowledge and skill involved in this restoration is downright awe-inspiring.

At my University (Swinburne, Melbourne, Australia) I studied Software Engineering with a minor in Digital Electronics. They said all along the goal wasn't for us to be as competent as the Electrical/Electronic Engineers, but to teach us their language and the basics so we could work together. It was great. My degree is accredited by the Australian Institute of Engineers.

At ANU I took one of our (quite few) digital electronics courses that taught me how to design simple digital logic on FPGAs. It ended up being probably one of my three favourite courses of my degree.

I think what I got out of it was similar - I'm obviously not nearly as knowledgeable as a fully fledged electronics engineer, but I have some basic knowledge which allows me to cross the gap between software and hardware and truly appreciate the fact that it is actually possible to get from just having a pile of logic gates to having something resembling a processor.

To anyone reading this who's currently a CS major - if you have the opportunity to do a course in digital logic design I'd highly recommend it. Regardless of what layer of the stack you end up working in, it's a lot of fun and very satisfying to understand how this stuff works. If you do end up working fairly low in the stack it's particularly helpful - after uni I ended up working on kernel development at IBM where even though I don't work in hardware engineering I've found it helpful to have some of the background knowledge.

Re: Restoring YC's Xerox Alto day 8: it boots

#76

Post by david-given »

kens wrote: post #55
bogomipz wrote: post #51

This has really been a great series to read. Does anybody know where this will live when they are done restoring it?

It will probably be at the YCombinator office for a while but we haven't figured out a long-term plan. Any suggestions?

Gateway the ethernet from yours to the one in the museum? After all, they are supposed to be networked workstations...

Re: Restoring YC's Xerox Alto day 8: it boots

#77

Post by tluyben2 »

ChuckMcM wrote: post #66
tluyben2 wrote: post #63

Earlier quoted context omitted.

Agreed, just very hard to get one... C64s are still easy to get. Edit: also I do not think there is little point: it still allows people to get away from the computer as magic. Even though it does not completely compare to a modern system, once you have done this you will never think you system is performing magic or that some coding bug is the universe conspiring against you.

FWIW I might have an extra PDP-8/m :-)

I have a museum with over 1000 computers from 60-70-80s (oldest is from '62); what you want for it? :)

Re: Restoring YC's Xerox Alto day 8: it boots

#78

Post by pjc50 »

kens wrote: post #38
0x0 wrote: post #30

I'm trying to read the article on an iphone but every time I zoom out to see the full width article I get bounced over to an article about toothbrushes?! For the better part of a minute I was wondering if they had monkey-patched the disk controller with an electronic toothbrush?!

You must have swiped left to my earlier article where I did a teardown of a Sonicare toothbrush. I've removed Blogger's swipe left/right navigation, which I think is more distracting than useful, and I've re-enabled pinch to zoom, so hopefully the navigation will work better for you now. Also note that you can tap on a photo to get a high-resolution version (better than zooming will give you).

It's a little thing, but thankyou for reading feedback and responding like this with blog improvements.

Re: Restoring YC's Xerox Alto day 8: it boots

#79

Post by Gibbon1 »

linker3000 wrote: post #72
userbinator wrote: post #54

Earlier quoted context omitted.

The PC had no RTC, so DOS would ask you the date and time every time you booted it: https://en.wikipedia.org/wiki/File:PC_DOS_1.10_screenshot.pn... ...and if you accepted the default, as many people at the time did, it would be 1980-01-01 00:00:00. DOS and the PC actually had no Y2K problem, storing the number of years since 1980 in a single byte --- which will overflow after 2235. It is notable that there is no year…

Yeah, yeah, get me the EGA card/memory update that includes the Dallas real time clock!

Boggle. I'm amazed my old meat based brain can remember something like that 25 years later.

Re: Restoring YC's Xerox Alto day 8: it boots

#80

Post by linker3000 »

kens wrote: post #14
cnvogel wrote: post #7

Earlier quoted context omitted.

Probably out of fear that the signals might deteriorate with probes attached. But with a modern-ish logic-analyzer and the ancient original hardware (huge voltage swings, slow clock, very long busses), I doubt that the probes would make a discernible difference, would they?

Yes, you're right about the signals. The Alto has a 5.88 MHz clock which is very slow by modern standards, and the buses are a couple feet of wire-wrapped pins so the probes are unlikely to have any effect. I'm not sure modern-ish is the right word for the logic analyzer. It's a 1999 Agilent logic analyzer and I don't know how they managed to make it so slow. You can ftp a trace off it over Ethernet at the glacial sp…

Reminds me of my electronics R&D days on flight sims in the 1980s where the fix for one particularly edge-case timing issue was to replace a 74S TTL part (within a sea of 74S logic) with a 74LS one and INSIST that only 74LS parts were used in that particular socket. Job done, no need for more probing!
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