360rpm or not

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Kubi
Posts: 7
Joined: Sat Jan 16, 2016 11:47 am

360rpm or not

Post by Kubi » Sun Jan 17, 2016 1:04 pm

Hi Community,

I am very new to this.
I got a Casio FZ-10M derivate from Hohner and I tried to get this working again.
I've got a library of ~80 Disks with self-recorded material.
My trouble is, that the original Disk-Drive (Panasonic FD-235HF-A110) is not working properly and i want to replace this with a Disk-Emulator.
The FD-235HF is working with 360rpm. I have tried to replace the Disk-Drive with modified Drives like TAEC FD-235HF (360rpm mod) but this doenst work but I think this a Shugart Bus problem or the modifying of the drive is not really working.
So I connect the drives to the Kryoflux and start testing: dtc -ffilename.img -v360 -i4
The result is an image file with 1280kb. When I turn to the GUI version i can see different results. The original disks have always green tracks, some other Disks have orange tracks with a "H" (Hidden Data in the Header).
Some have a mix with grey (unformatted) or even red (bad tracks).
I have tried that with different drives and it seems that I get the best results with a unmodified Mitsumi D359T3 Disk Drive. I am not sure if this drive is working properly with 1,2 MB Disk without modifying.

But there is something that every constallation had in common: The DTC is always showing me 300rpm.
This is confusing me because I have seen screenshots with 360rpm.
I want to prevent that I going the wrong way. Maybe that doesn't matter but I am not sure. When I am testing with -v300 I got unknown tracks.

My questions are:

- does the 300/360 thing matter or not?
- does the orange colored tracks working?
- is a Disk with bad or unformatted sectors lost?

Best Regards,
Kubi

Feltzkrone
Posts: 255
Joined: Sat Jun 18, 2011 8:03 pm

Re: 360rpm or not

Post by Feltzkrone » Sun Jan 17, 2016 7:13 pm

Hi Kubi,

as for the 300/360 thing: The rpm of a drive matters to original hardware i.e. keyboards, snythesizers, computers, as they generally expect either 300 or 360 rpm and won't be able to successfully read data using a drive which doesn't meet that expectation.

KryoFlux works differently, it captures timings of flux transitions (many times per full rotation) and index signals (once per full rotation) and thus is absolutely independent of drive speed because flux timings relate to index signal timings. DTC will then try to interpret that information according to your choice: If you use -v300 it expects data as -written- by 300 rpm drives, if you use -v360 it expects data as written by 360 rpm drives. And this has nothing to do with the speed of the drive used for reading with KryoFlux.

When you get worse results by using -v300 it should be -v360 instead. When DTC shows you 300 rpm I bet it's the current rotational speed of the drive that you are using with KryoFlux, which may explain the problems that you have using the same drive as a replacement in your Hohner hardware (expecting 360 rpm but getting 300 rpm instead).

Orange colored tracks are absolutely normal for disks that have been written to with home equipment. Professional duplicators usually write whole tracks whereas home equipment usually writes single sectors only, leaving some small areas of garbage data where writing has started and writing has finished.

Disks with bad sectors or unformatted tracks are not necessarily lost. Some can be recovered by carefully cleaning the surface of the platter, especially when dirt or mould is visible.

Kubi
Posts: 7
Joined: Sat Jan 16, 2016 11:47 am

Re: 360rpm or not

Post by Kubi » Sun Jan 17, 2016 10:16 pm

Hi Feltzkrone,

Thank you for your reply.
That indicates that the original disk drive JU-255 is damaged because the software also tells me that this disk is spinning at 300rpm and it have a lousy track dump. Even with the original disks from the manufacturer.

Thank you for clarifying this.

Best Regards,
Kubi

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