Timeline for Did Steve Gibson's Spinrite actually do anything useful by "refreshing" the disc's magnetic domains?
Current License: CC BY-SA 4.0
14 events
| when toggle format | what | by | license | comment | |
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| Aug 1 at 18:39 | comment | added | supercat | ...allow a drive to physically write its tracking information with the aid of input from a factory's optical measuring equipment, but at some point the technology advanced to the point where that would have ceased to be practical. | |
| Aug 1 at 18:37 | comment | added | supercat | @dave: I don't know what details to storage technology occurred when, but hard drives evolved in such a way that tracking information needed to be written to platters before the platters were installed in drives, both because a drive whose disks didn't already contain such information would have no way of knowing where to move its heads, and also because the drive heads wouldn't be powerful enough to write such information even if they had some way of knowing where they were positioned. There may have been some drive makers that included electronics that could... | |
| Aug 1 at 10:52 | comment | added | dave | @ErikF - for framing, I regard the ST-506 as occurring relatively recently in the timeframe of interest to SE:RC. | |
| Aug 1 at 2:03 | comment | added | ErikF | @dave The last time I ever had/could deal with low-level formatting was in the ST-506 days with MFM and RLL. As soon as IDE came around, I don't think you could even do a true low-level format even if you wanted to. | |
| Jul 31 at 23:33 | comment | added | dave | @supercat - but I'm not really getting your point. Is it that there was/is a disk type where the low-level formatting is baked into the disk at the factory? I readily bow to your knowledge, but I'm saying that before that there was on-site formatting of packs. Although now I'm doubting whether I personally ever did that. | |
| Jul 31 at 22:53 | comment | added | dave | @supercat - 'for years' - but this is Retrocomputing SE, where the decades just melt away, and we can all still fit into our 28" waist Levi's 501s. | |
| Jul 31 at 19:39 | comment | added | supercat | ...to the parts of the glass where the resist was removed. The process can then be repeated for green and blue. Even if the position of the shadow mask relative to the screen surface is only specified e.g. +/- 1mm, the phosphor dots will be perfectly aligned with the shadow mask, because their position will be adapted to match whatever the shadow mask position happens to be. | |
| Jul 31 at 19:38 | comment | added | supercat | @dave: The magnetic field produced by the drive head when writing is so finely concentrated that it won't be able to affect magnetic flux states deeper within the media, and the drive will by nature adjust its behavior to accommodate any manufacturing variations in the mechanism. This approach reminds me a little bit of the way phosphor dots are put on a color CRT. The inside surface is coated with a resist layer, the screen is fed a signal to draw one color (eg. red), the parts of the resist layer that were hit with the beam are chemically etched, and then red phosphor is applied... | |
| Jul 31 at 19:34 | comment | added | supercat | @dave: For years, drives have often had tracking and synchronization data written at a physically depeer layer on the disk than user data, at lower density, in a way that allows it to be read independently of the user data. Equipment to record these markings needed to be extremely precisely calibrated, but a drive which could quickly move the head in and out in small increments could get by with much sloppier tolerances, since a drive could move somewhere near where it needed to go, read where it was, adjust its posiition, read where it was, and maybe perform a third adjustment if needed. | |
| Jul 31 at 17:06 | comment | added | Miss Understands | Yeah, but it didn't used to be. I specifically mentioned ST220 and the RLL era. | |
| Jul 31 at 17:00 | comment | added | dave | Low-level format was real. There are three things you need to do to a freshly-coated magnetic disk: (1) record track and sector markings, (2) check for sectors that cannot reliably be written and re-read, (3) write an empty file system. In computer systems that don't confuse meanings, these are called formatting, bad-block check, and initialize, respectively. Formatting on site was once needed because removable disk packs were not necessarily sold for a particular geometry. With fixed disks, and especially with integrated HDAs, 'low level' formatting can be done at factory. | |
| Jul 31 at 16:52 | comment | added | Miss Understands | @supercat So you're saying that the low level format is a myth? | |
| Jul 31 at 16:31 | comment | added | Mark Ransom | Older drives might have had some drift in the exact position of a track, resulting in offsets over time that would make it harder to read the bits. Newer drives use servo tracking to stick to the track precisely so drift doesn't happen. | |
| Jul 31 at 14:56 | history | answered | supercat | CC BY-SA 4.0 |