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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

#61

Post by vvanders »

raldi wrote: post #13
kens wrote: post #12

Earlier quoted context omitted.

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!)

Their assistance was really shrewd; I've been to the CHM in Mountain View before, but had never heard of the LCM and probably would never have gone before this, but now I'm definitely going to go the next time I'm up in Seattle.

I can highly recommend it. A team I was on did it as a team-building exercise and it was by far the best one of my career.

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

#62

Post by beachy »

tluyben2 wrote: post #60
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.

If you have the time and interest, get a broken 80s system and a cheap logic analyser. Try to fix it; I learnt most that way. Or get a working and a broken and first analyse the working and then the broken.

A PDP-8 is an awesome machine if you want to get into this kind of thing. Not so big you'll need to extend your house. Front panel that will impress your friends. TTL logic that you can debug using a scope, replace dead chips with your soldering iron. Unless you have a problem in the core memory :)

As with all old iron there is little point to it but I used to love it.

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

#63

Post by tluyben2 »

beachy wrote: post #62
tluyben2 wrote: post #60

Earlier quoted context omitted.

If you have the time and interest, get a broken 80s system and a cheap logic analyser. Try to fix it; I learnt most that way. Or get a working and a broken and first analyse the working and then the broken.

A PDP-8 is an awesome machine if you want to get into this kind of thing. Not so big you'll need to extend your house. Front panel that will impress your friends. TTL logic that you can debug using a scope, replace dead chips with your soldering iron. Unless you have a problem in the core memory :) As with all old iron there is little point to it but I used to love it.

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.

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

#64

Post by bogomipz »

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?

The Computer History Museum in Mountain View? Its close enough that you could still go visit it too :)

I think you should talk to them anyway as the material in these blog posts would make for a really amazing talk.

http://www.computerhistory.org/

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

#65

Post by AdamJacobMuller »

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 am also a software engineer (in part) and I basically agree with everything you say, except, I don't really feel like I'm missing out.

I have a huge amount of respect for the people doing this, and it does look like great fun for them to do it and I do enjoy reading about them doing it but the idea of hooking up hundreds of logic probes and analyzing code on a logic analyzer sounds like something that is, personally, a nightmare. But, this is coming from a guy who hasn't picked up a soldering iron without burning himself on it.

That said, the EE class I took in college was by far my favorite (and the only one I regularly attended -- before I left), but I was always more entranced by the theoretical than the practical side of it.

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

#66

Post by ChuckMcM »

tluyben2 wrote: post #63
beachy wrote: post #62

Earlier quoted context omitted.

A PDP-8 is an awesome machine if you want to get into this kind of thing. Not so big you'll need to extend your house. Front panel that will impress your friends. TTL logic that you can debug using a scope, replace dead chips with your soldering iron. Unless you have a problem in the core memory :) As with all old iron there is little point to it but I used to love it.

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 :-)

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

#67

Post by intrasight »

This has been a fun series to track. I used an Alto when I was in college. As an EE, we had to wire-wrap a computer using bit-slice and TTL parts. Definitely the hardest lab component course I took (there were much harder theoretical courses).

So a new Broadwell-EP Xeon chip has like 7 billion transistors. I'm trying to imagine this kind of computer hardware archeology as it will be done thirty years from now.

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

#68

Post by kens »

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 :-)

Must...Resist...

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

#69

Post by kens »

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.

I happened to come across the Alto's time handling code [1] while looking for something else. The Alto counts seconds since Jan 1, 1901 and the time can run until 2036 since it uses a 32-bit value. (Unix time in comparison runs from 1970 to 2038; it runs half as long because it loses a bit by using a signed value.)

The point of this is the Alto can handle dates until 2036, but will run into problems two years before Unix self-destructs in 2038.

[1] http://xeroxalto.computerhistory.org/Indigo/AltoSource/TIMES...

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

#70

Post by ago »

jacquesm wrote: post #22
astrange wrote: post #21

Earlier quoted context omitted.

And "flash memory" itself can't be flashed anymore. Isn't it called that because you could erase an EEPROM with a light?

No, flash is called flash because of the speed, relative to other programmable memories that can be erased.

"Flash memory (both NOR and NAND types) was invented by Fujio Masuoka while working for Toshiba circa 1980. According to Toshiba, the name "flash" was suggested by Masuoka's colleague, Shōji Ariizumi, because the erasure process of the memory contents reminded him of the flash of a camera."

https://en.wikipedia.org/wiki/Flash_memory#History

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