Can KryoFlux detect drive capabilities ?

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TeaRex
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Re: Can KryoFlux detect drive capabilities ?

Post by TeaRex »

mr.vince wrote:II would recommend using a degausser anyway for pre-formatted 5.25" media, at least when writing 48TPI disks (e.g. C64) in a 96TPI (standard HD PC) drive. This will make sure there are no leftovers from a 48TPI head between tracks (as the 96TPI head will only write about half the width).
Getting a bit off topic, but: do you really need a degausser for that, or is it enough to just "write zeros" (i.e. write with no flux reversals) across the whole disk surface, including the "in between" tracks before you start writing your user data?
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mr.vince
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Re: Can KryoFlux detect drive capabilities ?

Post by mr.vince »

There's a gap between tracks, so we need to degaus. At a1k.org Herzi already modified broken 3.5" drives to work as degaussers (with permanent magnets built in). The same could be done for a 5.25" mechanism I guess.
TeaRex
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Re: Can KryoFlux detect drive capabilities ?

Post by TeaRex »

mr.vince wrote:There's a gap between tracks, so we need to degaus. At a1k.org Herzi already modified broken 3.5" drives to work as degaussers (with permanent magnets built in). The same could be done for a 5.25" mechanism I guess.
Hmmm.... I guess then I'll just use my trusty Commodore 1571 drive and step it in half-tracks to delete the disk. Given its wider head, that should cover the whole surface.
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Malvineous
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Re: Can KryoFlux detect drive capabilities ?

Post by Malvineous »

mr.vince wrote:at least when writing 48TPI disks (e.g. C64) in a 96TPI (standard HD PC) drive. This will make sure there are no leftovers from a 48TPI head between tracks (as the 96TPI head will only write about half the width).
I've heard anecdotes that writing DD disks in HD drives don't work as well (when read back in DD drives) because of this - the tracks are half the expected width.

Will 5.25" write support allow you to duplicate every second track to solve this (if that would even work), or if you want a true DD disk will you need to write it with a DD drive?
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mr.vince
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Re: Can KryoFlux detect drive capabilities ?

Post by mr.vince »

TeaRex wrote:Hmmm.... I guess then I'll just use my trusty Commodore 1571 drive and step it in half-tracks to delete the disk. Given its wider head, that should cover the whole surface.
Degaussing is the solution...


Malvineous wrote:
mr.vince wrote:at least when writing 48TPI disks (e.g. C64) in a 96TPI (standard HD PC) drive. This will make sure there are no leftovers from a 48TPI head between tracks (as the 96TPI head will only write about half the width).
I've heard anecdotes that writing DD disks in HD drives don't work as well (when read back in DD drives) because of this - the tracks are half the expected width.

Will 5.25" write support allow you to duplicate every second track to solve this (if that would even work), or if you want a true DD disk will you need to write it with a DD drive?
No, DD and HD heads use the same track, so you won't run into this problem. Most problems arise from HD media used as DD media (hole taped) or drives that don't care about DD (missing HD detection switch thus working in HD mode with HD coercivity all the time).

Writing 48TPI disks in a 96TPI drive will use double stepping, like the replicators did. Just make sure the disk is empty before -> degauss.
TeaRex
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Re: Can KryoFlux detect drive capabilities ?

Post by TeaRex »

mr.vince wrote:Degaussing is the solution...
Hmmm.... hold the 5.25" disk it to the screen of a CRT and let it go *ZING*? At least my trusty 21" CRT is very loud and pretty violent when degaussing. Or is that more bark than bite?
mr.vince wrote:No, DD and HD heads use the same track, so you won't run into this problem.
We're talking about 5.25" media here, right? So it's not true that DD 5.25" heads have a wider gap than HD 5.25" heads? Then why can't they use adjacent "half tracks" (= 96 TPI tracks) even if you can step them in half tracks? Of course in 3.5" drives both DD and HD use 80 tracks per side, so this obviously is no issue with 3.5" media.
mr.vince wrote:Most problems arise from HD media used as DD media (hole taped) or drives that don't care about DD (missing HD detection switch thus working in HD mode with HD coercivity all the time).
Again, we're talking 5.25" right? How do 5.25" HD drives even detect the media type? As there obviously is no DD/HD detection hole in 5.25" media. And if they can't detect it, how do they adjust?
mr.vince wrote:Writing 48TPI disks in a 96TPI drive will use double stepping, like the replicators did.
So the replicators used HD 5,25" drives even when producing, say, Apple II media? When did the replicators even enter the market, AFAIK the HD 5.25" drive is a child of the 1984 IBM PC/AT, six years after the Apple Disk II entered the market, right? Or did HD 5.25" drives and replicator machines exist before that?
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mr.vince
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Re: Can KryoFlux detect drive capabilities ?

Post by mr.vince »

Good morning! I have no idea why I mixed up 3.5" and 5.25", maybe the right half of the brain was doing something different.

Of course 5.25" HD drives use a narrower head and 80 tracks, as DD drives will use 40 tracks only.

5.25" drives adjust to HD writing via PIN 2 of the 34P connector, which is signalling HD. It's up to the user (or application) to set this signal correctly.

Yes, replicators did use HD drives as soon as possible. We can track down commercial replication to the very early 80s. I think the earliest sample we have is from 1982 or 1983. We can see the replicator ID placed in an unused track that will reveal e.g. the stepping set.

Degaussing needs to be done with a special device, and beware... do this in a separate room without other devices. It uses a very strong coil to induce a very strong field. It's also possible to build such thing with two permanent magnets and a dead drive. We do have such an eraser for 3.5" media. A small microcontroller will turn on the motor and step the head from 0 to 84... and the disk is guaranteed to be empty afterwards. It was built by Herzi at a1k.org.
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