Hitachi FDD-412A 8 inch floppy drive

Jeff
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by Jeff »

Can you share the stream files ?

CNC_USER
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by CNC_USER »

I played with Kryoflux and disk drive connections and finally managed to get some results. First track appears to be FM, all others MFM. A bit of headaches made FDD-412A signal pinout names. MFM GATE shoud be connected to DENSITY LINE pin (pin 2 on 34 pin Kryoflux floppy connector).

brightcaster
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by brightcaster »

The MFM gate on the hitachi FD-4122A actually does a little bit more than changing filters alone (like density line does). It looks as if it switches the inbuilt data and clock separator from FM to MFM decoding also! Without setting MFM gate you get very obscure data while decoding MFM. It still looks more like FM (2 bands), but with a lot of bits at wrong positions!

David

PS: Details are at https://forum.kryoflux.com/viewtopic.ph ... 6&start=10

CNC_USER
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by CNC_USER »

brightcaster wrote:
Sun May 29, 2022 6:59 pm
PS: Details are at https://forum.kryoflux.com/viewtopic.ph ... 6&start=10
This is my topic there. :D Im now stopped at writing new files back to disks.It seems that it is possible to decode/find a way how to change NC specification bits to add new functions with the help of HEX editor. :wink:
Jeff wrote:
Fri May 27, 2022 9:18 pm
Can you share the stream files ?
They are in brightcaster's shared link.

brightcaster
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by brightcaster »

To get things right you have to take track 0.0 from this set (drive set to FM mode):

https://failiem.lv/u/mncvs7ejy

And all the other tracks from this set (drive set to MFM mode):

https://failiem.lv/f/szfgdna3g

Or am I wrong because the two images are from two different floppies?

David

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