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A 1970s Cray-1 hard drive has been imaged

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Re: A 1970s Cray-1 hard drive has been imaged

#31

Post by arjunnarayan »

ilamont wrote: post #24
ilamont wrote: post #15

About four years ago I interviewed Ray Kurzweil, and asked him about the issue of old data formats. In Singularity or one of his earlier papers or books, he had lamented the inaccessibility of old data, which prompted me to ask about the role of standards. His response: We do use standard formats, and the standard formats are continually changed, and the formats are not always backwards compatible. It's a nice goal,…

Related thought: The "Rosetta Project" ( http://rosettaproject.org/ ) aims to build a publicly accessible library of human languages. Besides the website, part of the original concept was to seed the world with "Rosetta Discs", metal spheres with an approximately 2,000-year lifespan, etched with optically readable samples of thousands of written languages. Future humans who found the discs would be able to review and…

I like the way the disk begins in eye-readable scale and tapers down. But why not continue this even further? At some point, when enough exposition has been done so that the corpus is fairly understandable, you could then introduce the concept of binary encoding. And then after a few short examples and mappings, then continue the rest of the disc in binary form.

One could theoretically take this further by then explaining how we built our primitive computers, some simple math, and continue.

I would love an accompanying Rosetta project that was in just one language, but exposited our understandings of math, physics and computer science so that some civilization that discovered the twin discs could use the first one to learn English (as long as they knew or could decipher at least one of the languages) and the second one to reconstruct our understanding of math, physics and computer science and rebuild a 2000 AD era computer, and finally input to it a tar.gz dump of all of Wikipedia.

Re: A 1970s Cray-1 hard drive has been imaged

#32

Post by DerekL »

ColinDabritz wrote: post #28

This reminds me of the 'Digital Needle' project, which was a hacking project done by Ofer Springer back in 2002. The idea was to use a flatbed scanner to play a vinyl record. http://www.phys.huji.ac.il/~springer/DigitalNeedle/ It came surprisingly close. Perhaps with today's technology we could do better?

A company called ELP sells laser-based turntables. They start at $9900.

Re: A 1970s Cray-1 hard drive has been imaged

#33

Post by pflanze »

mjb wrote: post #8
ericHosick wrote: post #5

Specs on storage module drive: http://ia600707.us.archive.org/32/items/9760_9762_oct73/9760... . The unit has an average seek time of 30ms in 1973. Today, in common 7200 RPM drives, it seems to be around 8-9ms. There is only a factor of improvement of 3 to 4 times. I find this pleasantly surprising.

Latency has been scaling worse than almost any other factor for nearly the entire history of computing. The latency/throughput ratio for storage, networking, memory, cache and almost everything else has been rising continuously since the 70s and is likely to carry on rising. This is going to have big consequences for the way that we design systems in the future. Transferring a large amount of data is going to be chea…

> 30ms for a Cray 1 was only 2400 clock cycles

2.4 million clock cycles. (According to Wikipedia, the Cray-1 had a 80 MHz clock, which you also mention in your other post.)

Re: A 1970s Cray-1 hard drive has been imaged

#34

Post by mjb »

pflanze wrote: post #33
mjb wrote: post #8

Earlier quoted context omitted.

Latency has been scaling worse than almost any other factor for nearly the entire history of computing. The latency/throughput ratio for storage, networking, memory, cache and almost everything else has been rising continuously since the 70s and is likely to carry on rising. This is going to have big consequences for the way that we design systems in the future. Transferring a large amount of data is going to be chea…

> 30ms for a Cray 1 was only 2400 clock cycles 2.4 million clock cycles. (According to Wikipedia, the Cray-1 had a 80 MHz clock, which you also mention in your other post.)

You are indeed correct. That's kind of how it worked in my head (about 12x change) but I didn't type it that way for some reason.

Re: A 1970s Cray-1 hard drive has been imaged

#35

Post by ams6110 »

0x12 wrote: post #16
ericHosick wrote: post #5

Specs on storage module drive: http://ia600707.us.archive.org/32/items/9760_9762_oct73/9760... . The unit has an average seek time of 30ms in 1973. Today, in common 7200 RPM drives, it seems to be around 8-9ms. There is only a factor of improvement of 3 to 4 times. I find this pleasantly surprising.

Average seek time across a disk which is much larger physically than the disks in use today. It wasn't rare at all to find fair sized servos (as opposed to steppers in consumer grade stuff in the 80's) in those old disk pack units (the size of a washing machine). You can't really compare 'common 7200 RPM drives' of today with a top-of-the-line medium from the 70's, physics didn't change at all in that time. That's wh…

The actual mass of the heads and arms was an issue as well; you had to be careful not to seek back and forth at the natural resonance frequency of the cabinet or the "washing machines" would start walking across the floor.

Re: A 1970s Cray-1 hard drive has been imaged

#36

Post by WalterBright »

About a year ago, I needed to get some data off some old PDP-11 8" diskettes. Fortunately, an old friend had an LSI-11 in his closet with the disk drive. He hadn't run it in years, but it fired right up, and the disks read perfectly, and he sent me the images.

Whew!

(thank you, Cheshire Engineering!)

Re: A 1970s Cray-1 hard drive has been imaged

#37

Post by WalterBright »

WalterBright wrote: post #36

About a year ago, I needed to get some data off some old PDP-11 8" diskettes. Fortunately, an old friend had an LSI-11 in his closet with the disk drive. He hadn't run it in years, but it fired right up, and the disks read perfectly, and he sent me the images. Whew! (thank you, Cheshire Engineering!)

My PDP-10 software, unfortunately, was gone for good. It was all on a magtape, and the drive that wrote it was way out of spec and the tapes were unreadable on any other drive. (sob)

Re: A 1970s Cray-1 hard drive has been imaged

#38

Post by Maci »

danbee wrote: post #20
0x12 wrote: post #6

That's pretty impressive. Not only did they image the disk, it was a disk that had had a head crash and one damaged head which they managed to restore to functioning well enough to capture the data. Now of course the big question: what is on that disk?

I believe the head crash occurred on a different disk pack, one that they were using to test it.

From the Paper:

Unfortunately, within 30 seconds of the heads being loaded a high-pitched whining noise began to be emitted from the drive, implying a potential head-to-disk contact was taking place. The drive was then powered down and the disk pack and heads were carefully examined. Thorough examination revealed that Head #4 on the drive (which reads the bottom surface of the lowest data platter) had 'crashed' into the disk surface and scraped away a concentric ring of oxide material, permanently damaging the platter. This is a good time to point out the advantages of not experimenting with your primary source material when performing digital archeology experiments!

Src: http://www.archive.org/details/2011-cdc-disk-archaeology-fen...

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