Post #1673566
2025-10-26 00:15 UTC
Replies (36)
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@discatte@digipres.club 2025-10-26 00:18
@altomare@oldbytes.space oh to be a disk lint speeding by at 58 miles per hour. :neocat_floof__w_:
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@ltning@pleroma.anduin.net 2025-10-26 00:30
@altomare@oldbytes.space missed opportunity: bug for scale
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@futurebird@sauropods.win 2025-10-26 01:20
@altomare@oldbytes.space This is directly related to the chapter of "the book I can't talk about it until it is done" that I was writing today! I'm getting so close to being done it's making me nervous.
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@PetraOleum@cloudisland.nz 2025-10-26 01:24
@altomare@oldbytes.space 'micro inches' is a new measurement on me, but also dang
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@Hearth@plush.city 2025-10-26 01:29
@altomare@oldbytes.space of note is that those aren't microns in the dimensions there--people outside of very particular fields might not be familiar with the microinch or μ" (yes the symbol is a travesty), but those are indeed given in μ", not μm. So even smaller than you might think on first read! -F
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@mattmcirvin@mathstodon.xyz 2025-10-26 01:29
@altomare@oldbytes.space I 100% remember seeing this diagram somewhere Back In The Day. I don't think I was looking in that DEC manual, I think someone showed it to me.
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@imnotafeline@mastodon.online 2025-10-26 01:33
@altomare@oldbytes.space good vibes
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@RussSharek@mastodon.art 2025-10-26 01:57
@altomare@oldbytes.space I've known about this, but have never seen this chart before. That's amazing.
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@zl2tod@mastodon.online 2025-10-26 02:07
@altomare@oldbytes.space A copy of that chart was pinned to my office wall *mumble* decades ago. The RK05 was a 2.5MB single platter disk cartridge about 18" across, and yeah, they crashed a lot. https://en.wikipedia.org/wiki/RK05
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@soviut@hachyderm.io 2025-10-26 02:16
@altomare@oldbytes.space I like how they mentioned a smoke particle because there were undoubtedly people smoking around open hard drives in the 70s.
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@TracyTThomas@mastodon.beer 2025-10-26 02:17
@altomare@oldbytes.space How did it ever work?!?
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@sungo@social.sungo.space 2025-10-26 02:18
@altomare@oldbytes.space @RussSharek@mastodon.art they mean "micro inch", don't they? my dreams will be haunted by diagrams with micro inches...
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@StarkRG@myside-yourside.net 2025-10-26 02:39
@altomare@oldbytes.space Modern, super-high-density drives use helium partly because helium atoms are smaller than everything else in air (including hydrogen molecules, H_2).
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@zoowar@mstdn.social 2025-10-26 02:42
@altomare@oldbytes.space When I was at HP, I heard lore from back in the days when you could smoke in the office. Some guy notorious for smoking cigars walked up to one of the early Winchester drives and exhaled smoke from his cigar into the cabinet. The drive failed.
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@WesternInfidels@mefi.social 2025-10-26 03:01
@altomare@oldbytes.space The outer rim of a modern 3.5" 7200RPM disk travels at about 75 MPH relative to the heads. A fancy 10,000 RPM data-center drive would be about 104 MPH.
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@snorerot13@mstdn.social 2025-10-26 04:57
@altomare@oldbytes.space We had this diagram in the first facility I worked in
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@sfwrtr@eldritch.cafe 2025-10-26 05:40
@altomare@oldbytes.space Note that the important thing here is the smoke particles. If you are a sysop and you're in charge of the computer room, and especially if you are changing the disk packs, DO NOT SMOKE. If you smell of smoke, it b real bad, man!
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@chris@social.losno.co 2025-10-26 06:00
@altomare@oldbytes.space Meanwhile Americans use anything but the metric system. Micro inches?
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@karlauerbach@sfba.social 2025-10-26 06:08
@altomare@oldbytes.space We had some RK05s on some of our Unix machines at SDC in the mid 1970s. We never had a failure. But they were not used very much - we mostly used RP04 (and later, RP05/6) drives. My wife sold RK05s (and PDP-8s) when she worked at DEC.
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@jinna@gts.laalaa.land 2025-10-26 06:18
@altomare@oldbytes.space Ahhh, reminds me of diagnosing a bad fiber link to a piece of dandruff exactly covering the 50 micron core on a multimode LC connector.
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@atkelar@meow.social 2025-10-26 07:23
@altomare@oldbytes.space it's in inches... I want a banana for scale 😸
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@th@social.v.st 2025-10-26 07:54
@altomare@oldbytes.space based on that diagram would you say this RK05 DECpack platter is out of spec?
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@AbramKedge@beige.party 2025-10-26 07:57
@altomare@oldbytes.space on modern sealed drives, the firmware still has to deal with imperfectly flat disks. It uses head temperature to build a map of microscopically small bumps and distortions, and adjusts the fly-height dynamically to float above them.
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@scudderfish@weird.autos 2025-10-26 08:14
@altomare@oldbytes.space I wonder what the numbers for modern disks are like.
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@bitbraindev@mastodon.gamedev.place 2025-10-26 08:32
@altomare@oldbytes.space fascinating.
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@uk_csi@mstdn.social 2025-10-26 08:34
@altomare@oldbytes.space For many years I was an on-site engineer at a manufacturing business for my sins. I still remember the Monday morning I turned up for work to find 3 CDC 300 MB drives down and an unbootable system. The operator had found it unbootable when they arrived so had taken the disk pack out of the primary drive and tried it in 2 others after switching the drive IDs. Result was 3 crashed disk drives which to eventually repair exhausted the company's Europe wide stock of disk drive heads.😮
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@kbob@chaos.social 2025-10-26 08:59
@altomare@oldbytes.space And yet... I once hand-aligned an RK-05 platter. I loosened the six screws at the hub, slid the platter a little bit, retightened them, and iterated until the read errors stopped. No clean room, no mad skillz, just good luck.
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@vegard@mastodon.social 2025-10-26 09:11
@altomare@oldbytes.space I had a ~3 GiB hard drive in the iMac G3 era that I ran for months with the cover off, no issues. The spinning disk generated a wind. Showed it off to friends. So weird
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@rogerparkinson@mastodon.nz 2025-10-26 09:32
@altomare@oldbytes.space this was up on the wall at my first real computer job in the late 70s, courtesy of a DEC engineer. A couple of years later, different job, and they decided to have the disks cleaned. My response was WTF, but it wasn't up to me. A few days after the clean, I came into the office to find one of the drives was screeching, and there were a lot of magnetic flakes everywhere. That drive had crashed quite horribly. Amazingly, the idiots who had insisted on the cleaning talked their way out of responsibility.
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@grant_h@mastodon.social 2025-10-26 10:17
@altomare@oldbytes.space somewhere I read that if you scaled the read/write head up to the size of a jumbo jet, it would be doing Mach2, 2metres above the surface of a cornfield, counting individual stalks as it flew over.
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@tkinias@hcommons.social 2025-10-26 13:42
@altomare@oldbytes.space so weird to see inches being used in this context
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@TerryHancock@realsocial.life 2025-10-26 16:30
@altomare@oldbytes.space Intriguing: assuming the standard 7200 RPM 3.5 in disk most common for large internal hard drives, the edge should be a little slower than this -- about 37mph. I wonder if the "flying height" has changed at all? Can definitely see why these things are assembled and repaired in cleanrooms!
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@derHinek@troet.cafe 2025-10-26 16:49
@altomare@oldbytes.space Wait, a technical document, using micro inch as units? 😳
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@OpenComputeDesign@linuxrocks.online 2025-10-26 16:49
@altomare@oldbytes.space Hard drives are technologically so much more impressive than SSDs imo
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@RueNahcMohr@infosec.exchange 2025-10-26 17:25
@altomare@oldbytes.space hehehe 13" diameter....
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@RyeNCode@mstdn.ca 2025-10-27 00:18
@altomare@oldbytes.space Well.. the drive I have open and write a text file to so The Learning Ones can see the platters spin and the arm swing still mostly works. I should check the SMART report on that drive for funzees 😈