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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

#31

Post by rjsw »

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…

Have you tried a different ethernet switch connected to the logic analyzer ? One cause of really slow transfers is one end getting the full/half duplex negotiation wrong.

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

#32

Post by byebyetech »

cpr wrote: post #24
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.

Probably will crash if you told it correctly. You know, the old Y2K problem. ;-)

Yup, It will overflow its mind!

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

#33

Post by zakki »

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?!

I think the page navigation is using "slide to the left/right". Probably your zoom movement detected as a page navigation

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

#34

Post by colejohnson66 »

cpr wrote: post #24
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.

Probably will crash if you told it correctly. You know, the old Y2K problem. ;-)

As someone who was too young at the time, why would it crash? I thought the Y2K problem was just programs only storing the last two digits. So 2016 would be stored as 16 and displayed as 1916.

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

#35

Post by eric_the_read »

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…

Is it a 16500? If so, you might see if you can scrounge up a 16505A, which might be able to network much faster (plus, it supports VNC and has a nice (for the time) graphical display. The 16505A is basically a PA-RISC pizza box that hooks up to the 16500 via a SCSI cable on the back, and adds some X11/Motif GUI happiness on top. I took a quick look around eBay and saw one for ~$275, but you might be able to get one cheaper if you look.

Side note: it was called a "Prototype Analyzer" because it was meant for analyzing prototypes, but we had more than one customer tell their salesperson to come back later when it was out of the prototype stage.

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

#37

Post by djsumdog »

colejohnson66 wrote: post #34
cpr wrote: post #24

Earlier quoted context omitted.

Probably will crash if you told it correctly. You know, the old Y2K problem. ;-)

As someone who was too young at the time, why would it crash? I thought the Y2K problem was just programs only storing the last two digits. So 2016 would be stored as 16 and displayed as 1916.

Yep, that's pretty much it.

You could run into crashes if something was dependent on the date being in the future since when the machine was built (and hence you get a negative number when you shouldn't have), or if the machine was alive between 1999 and 2000 (in which case the BIOS or applications may complain because you've gone back in time).

This /mostly/ affected date formats. Well built systems and programs measured time in seconds since the epoch on operating systems that supported that time representation format.

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

#38

Post by kens »

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).

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

#39

Post by djsumdog »

kens wrote: post #12
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.

We're building a FPGA-based disk emulator that we could connect to the Drive to rewrite the junk disk, but we don't have that ready yet. The Living Computer Museum could have rewritten our disk for us, but that would have required sending our disk to Seattle first so they just sent us a new disk. (The Living Computer Museum has been extremely helpful, so visit them if you're in the Seattle area!)

Recycle PC is another Seattle shop with a cute little museum. It has old Amigas, Apples, Xerox, et al systems. Unlike the Living Computer Museum, they're not functional (or they might but, but they're turned off).

You can't look inside any of the bigger units (you'll be asked to leave if you do), but you can press the keys on the older mechanical and non-mechanical keyboards if you're a keyboard nerd.

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

#40

Post by kens »

eric_the_read wrote: post #35
kens wrote: post #14

Earlier quoted context omitted.

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…

Is it a 16500? If so, you might see if you can scrounge up a 16505A, which might be able to network much faster (plus, it supports VNC and has a nice (for the time) graphical display. The 16505A is basically a PA-RISC pizza box that hooks up to the 16500 via a SCSI cable on the back, and adds some X11/Motif GUI happiness on top. I took a quick look around eBay and saw one for ~$275, but you might be able to get one c…

The logic analyzer is a 1670G; Marc collects vintage HP equipment, although technically this is Agilent.
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