Hitachi FDD-412A 8 inch floppy drive

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m.vgunten
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Joined: Sat Jan 18, 2020 5:56 pm

Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten »

Dear disk experts

I am trying to emulate/replace a Hitachi FDD-412A 8" floppy drive with my HxC Floppy Emulators (have both SD and Gotek). Unfortunately I do not have any documentation for this drive and its 50-pin IDC ribbon cable connector. It also seems impossible to find any details in the web :(.
The only thing I understand: it is not a standard Shugart connector (NOT as documented under https://old.pinouts.ru/HD/8InchDisk.shtml)!

Has anybody successfully replaced this kind of floppy drive? Who can deliver further information about IDC pinout, signals, ...?

The drive is connected to an Okuma Campus 5000 CNC System an data should be recovered to allow drive replacement.
As far as I know, the system works with SS and DS disks having SD and DD.
You can find pictures of the drive on http://www.retrocomputing.net/index.php ... Fotografie

Any help is appreciated - Thanks
Martin

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

Post by Jeff »

Lot's of IC on this drive... Can you make a better picture of the PCB ?

m.vgunten
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten »

Hi Jeff
Here are some images of the Drive and the PCBs.
Thanks for your help!
Martin
Attachments
FloppyDriveBottom.jpg
FloppyDriveBottom.jpg (122.8 KiB) Viewed 1199 times
FddPcbTop.jpg
FddPcbTop.jpg (171.69 KiB) Viewed 1199 times
FddPcbBottom.jpg
FddPcbBottom.jpg (165.45 KiB) Viewed 1199 times

m.vgunten
Posts: 9
Joined: Sat Jan 18, 2020 5:56 pm

Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten »

Trying to understand the pin assignments on the 50-pin IDC connector I followed the PCB traces ... still a work in progress.
I will also try to find some Okuma Maintenance Manuals.
Attachments
Hitachi_FDD-412A-IDC_50p.png
Hitachi_FDD-412A-IDC_50p.png (200.19 KiB) Viewed 1189 times
Last edited by m.vgunten on Sun Jan 19, 2020 2:29 pm, edited 1 time in total.

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

Post by Jeff »

I use here an YD-180 to dump 8" floppy disks and this one also use a non-standard pinout, maybe this is the same as your drive pinout.
The YD-180 is equivalent to this one :
https://deramp.com/downloads/floppy_dri ... Manual.pdf

If you have an oscilloscope you can check if the read data line match with the above pdf.

m.vgunten
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Joined: Sat Jan 18, 2020 5:56 pm

Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten »

Unfortunately it is not looking like a YD-180 pinout. I have most of the signals on odd pin numbers and measured the /INDEX pulse on pin 7. Just updated the table above ...
Thank you anyway!

m.vgunten
Posts: 9
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten »

Here some additional images of the Floppy Controller PCB.
FdcPcbTop.jpg
FdcPcbTop.jpg (158.36 KiB) Viewed 1156 times
FdcPcbBottom.jpg
FdcPcbBottom.jpg (124.46 KiB) Viewed 1156 times

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

Post by Jeff »

Is there a NEC 765 floppy controller ?

m.vgunten
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten »

Bingo! :D

Thanks a lot your hint will help finding the signals on the floppy connector!
NEC-D765AC.jpg
NEC-D765AC.jpg (23.25 KiB) Viewed 1141 times
NEC-D765AC-pinout.jpg
NEC-D765AC-pinout.jpg (9.67 KiB) Viewed 1141 times
http://www.cpcwiki.eu/imgs/f/f3/UPD765_ ... _OCRed.pdf

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

Post by Jeff »

m.vgunten wrote:
Mon Jan 20, 2020 10:08 pm
Bingo! :D

Thanks a lot your hint will help finding the signals on the floppy connector!

NEC-D765AC.jpgNEC-D765AC-pinout.jpg
http://www.cpcwiki.eu/imgs/f/f3/UPD765_ ... _OCRed.pdf
Yes. And we now know that the sector format used is pretty standard ;).

m.vgunten
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten »

Updated pin assignments on the 50-pin IDC connector after having a closer look to the floppy controller PCB ... still a work in progress.
Hitachi_FDD-412A-IDC_50p.png
Hitachi_FDD-412A-IDC_50p.png (57.33 KiB) Viewed 1038 times

m.vgunten
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten »

I can now control the floppy drive and read some date on the /RD pin - see bottom line in diagram below.
I further assume data separator clock /SEPC and data /SEPD on the two lines above (D16&D17) ... but I'm not sure at all!
FdReadDataSample.png
FdReadDataSample.png (60.67 KiB) Viewed 1038 times

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

Post by Jeff »

m.vgunten wrote:
Sun Jan 26, 2020 6:30 pm
I further assume data separator clock /SEPC and data /SEPD on the two lines above (D16&D17) ... but I'm not sure at all!
Yes for sure this is data separator outputs !

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

Post by joeyd »

The pin out is the same as a NEC FD1165 the NEC drive has EITHER a 50 pin card edge or 50 pin IDC the pins outs #'s are the same for both.
There is a gent out there in the New England area of the US that sells a 50pin adapter to go to shugart 34 pin. I have an extra if he is no longer selling them.

Be aware this particular floppy drive does DS/DD but it is a DS/HD drive!! When it is in HD mode (if your disks are labeled HD256,HD512 or HD1024) they are very very unique media its about a 6MB floppy drive in HD mode using the proper controller.
If you have any HD media you want to get rid of I'd be interested in it.
Joe

m.vgunten
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten »

Dear Joe
Thank you very much for your hint.
Do you mean the "FDADAP floppy disk adapter"? If not, please let me know some more details about it.
Unfortunately, the discs are in short supply also for us and we have no HD media left.
Thx Martin

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