One-pass "flippy" disk support is here!

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mr.vince
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One-pass "flippy" disk support is here!

Post by mr.vince » Sun Oct 09, 2011 9:42 am

You are not telling us here that you are writing an IPF from a 3.5" source disk to a 5.25" target disk?

TeaRex
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Re: One-pass "flippy" disk support is here!

Post by TeaRex » Sun Oct 09, 2011 6:00 pm

I am! What else CAN I write to a 5.25" target disk with KryoFlux at this point in time? This is entirely for testing. If there is anything that's inteded for 5.25" disks in the wild that can be written by KryoFlux, I'd be more than happy to substitute that.

I wrote IPFs from seemingly unprotected Amiga games (e.g. Monkey Island and some Infocom games) to 5.25 inch "2D96" floppies in a 5.25" HD floppy drive, then read them back to ADF. The magnetic material should certainly be able to support that, shouldn't it? It worked without a hitch in another floppy drive (Epson SD-600), and it was problematic only for tracks in the mid to upper 50s on my modified drive, as I wrote.

My original idea was simply to determine whether the drive's alighment after the mofication was still good enough to squarely hit the narrower tracks of HD disks, so since I couldn't find any HD 5.25" disks (blanks or prerecorded) I came up with the idea I described above - writing some floppies in other drives and reading it back with the modified drive, and vice versa. That's when I hit on the problem. I now found one pre-recorded HD 5.25" disk, an "Ultima Underworld" demo disk from 1992, and it worked in the drive. But as I said the problem seems to affect only writing disks in the modified drive, not reading in it.

Or is this whole thing to be expected because pre-compensation simply has to be different for 5.25" media as opposed to 3.5" media? Unfortunately I'm not really up to snuff as regards stuff that's even more low level than MFM or GCR encodings.

TeaRex
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Re: One-pass "flippy" disk support is here!

Post by TeaRex » Mon Oct 10, 2011 1:24 pm

I've found another small problem with the negative seeking: If you send the head to a negative position, then immediately press CTRL-BREAK and repeat the dtc command before the firmware has moved the head back to track 0, the drive will try to go even further down, which (on my Mitsumi drive) rather violently knocks it against the physical stop and makes the head's attachment to that spiral threaded thingy (for which I don't know the correct English term) jump out of the spiral grove.

I'd suggest never seeking below track zero without first going at least one step above track 0 with the bypass disabled, to ensure the head's position is right. Also it might make sense not to quit back from dtc to the command line on CTRL-BREAK or CTRL-C until the track zero bypass circuit is disabled and the head is known to be back at or above track 0.

One more thing, when the drive leaves the negative tracks and goes back to track 0 during "flippy" dumping, the drive will quickly "knock" back and forth once and I will receive the message "00.0: Control command rejected by device". However dumping will continue after that, so it is merely a cosmetic problem.

And while I'm at it: shouldn't "-y" imply "-b-8"?

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IFW
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Re: One-pass "flippy" disk support is here!

Post by IFW » Mon Oct 10, 2011 4:56 pm

What you suggest cannot be done as it would mean every single seek below 0 would grind the head back and forth to ensure it's at the correct position - not something you really want...

Probably the best thing would be to disable CTRL-C.

Yes, passing track 0 results in no track0 signal for some reason when moving in, rather than out (towards track0) - I'll investigate that eventually, but there is not much benefit as it works as is. Hence you get the warning, and the firmware recalibrates the head.

No, I wanted the system to be completely flexible including track offsets used hence the the three parameters, -y, -a, -b can be independently adjusted.

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IFW
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Re: One-pass "flippy" disk support is here!

Post by IFW » Mon Oct 10, 2011 4:58 pm

Mixing up DD and HD content is not a good idea and may or may not work.
Nothing to do with KryoFlux...

TeaRex
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Re: One-pass "flippy" disk support is here!

Post by TeaRex » Mon Oct 10, 2011 6:37 pm

IFW wrote:Mixing up DD and HD content is not a good idea and may or may not work.
If you refer to my problems with readability on tracks in the 50s: As far as I can see, I didn't mix DD and HD content. I wrote DD IPFs to DD floppies. Yes, I did so in a HD 5.25" drive (not because I would want 5.25" Amiga disks for productive use, but for testing). That's supposed to work, right? Or should one use only DD drives to write DD content?

Or are you referring to something else, or just giving a general statement unrelated to anything specific that I wrote?

TeaRex
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Re: One-pass "flippy" disk support is here!

Post by TeaRex » Mon Oct 10, 2011 6:44 pm

IFW wrote:What you suggest cannot be done as it would mean every single seek below 0 would grind the head back and forth to ensure it's at the correct position - not something you really want...

Probably the best thing would be to disable CTRL-C.
Of course that would quite do the trick.
No, I wanted the system to be completely flexible including track offsets used hence the the three parameters, -y, -a, -b can be independently adjusted.
I'm not speaking against the ability of the user to adjust them independently. They do have default values however, and I'm merely suggesting that the *default* value of -b should be -8 rather than 0 in case -y is given. Or maybe it should simply be mentioned in the help text for -y, something along the lines of "you will probably need to use a modified drive and use -b-8 as well". But of course it is your software, and please feel absolutely free to disregard any and all useless suggestions.

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IFW
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Re: One-pass "flippy" disk support is here!

Post by IFW » Mon Oct 10, 2011 8:43 pm

No, rest assured I am considering every single request posted in our forum or sent in email, and yours making it default, but allow it to be overriden as needed makes perfect sense - thank you :)

Darkstar
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Re: One-pass "flippy" disk support is here!

Post by Darkstar » Tue Oct 11, 2011 8:02 pm

Okay, so I'm not exactly a hardware guy. I don't have a Dremel and I can't even begin to imagine why I would want to have this press-thingy :)

So is there anyone in (southern) Germany who could modify a drive for me? The good thing is that I have a JU-475-4AKO which I presume is the predecessor of the drive used in the tutorial, it looks almost 100% identical (the circuit board is different but the test points are still there)

I guess I could do the electronics part myself but I do need help with the "heavy machinery" (for me as a software guy, a soldering iron is the biggest tool I'd ever use ;-)

thanks
-Darkstar

TeaRex
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Re: One-pass "flippy" disk support is here!

Post by TeaRex » Tue Oct 11, 2011 11:17 pm

Darkstar, just FYI I did the mechanical part of the modification on my drive with nothing more than a file and a caliper (So you don't have to look it up: eine Feile und eine Schieblehre). Takes a bit longer but it worked just as well.

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