Samsung sfd-321b

Prophet (2169)

27-02-2014, 14:10

So I am following the hansotten/luppie instructions for building in this fdd into a turbo-R but unfortunatly I managed to obtain some supernew revision. Great... it looks like the rdy and dc jumpers are there together with opb and opa but DS0 and DS1 is no longer on the print and as the warning stated on the website: no HD sensor as well. It would have been easy if the datasheet for the SF12021AG controller could be obtained somewhere but somehow it seems this is worlds best kepped secret...

So I will have to do it with this FDD I have and I am not giving up on it that easily. The HD to DD conversion would be a cool bonus but the DS0 part is a must. So here are some questions to whose who have more experience in this than I do:

1.) pin 10 and pin 14 (motor enable0 and drive select 0) are not connected to anything. Pin 12 (drive select 1) however is. If I just connect the drive select pin to pin12 I expect the FDD to still go into B: Now when I compare this print to the one on the foto I have downloaded from hansotten's website there has to be a way to solder some way around to still get DS 0 any ideas?

2.) pin 2 is in the open so it is not connected. The website states for pin 2: "Solder a wire between DC and OPB (to put DC on pin 2)" so if I just solder a wire from DC to pin 2 directly. will this work?

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Par luppie

Paladin (869)

27-02-2014, 14:26

I've spended almost 1 year on getting it to work in a Panasonic Machine but without luck.
Soldering the DS0 on the cable to pin 14 and ME on the cable to pin 16 on the drive will do to get the drive work as A:

But....... the lack of pin 2 to do density select (and the lack of the HD switch) makes this drive a HD only drive. I've had it working during the process in testing it. It does read 720kb disk, it gives errors writing 720kb disks and it was unable to format 720kb disks.

This is also the reason that some new (USB) diskdrives are unable to format 720kb disks in Windows 7/8

Par Daemos

Prophet (2169)

27-02-2014, 15:09

This diskunit has the exact same controller as the older revisions. If we could find out which pin needs to be pulled low/high the density can be controlled.

Thanks to your full print foto luppie I have found the pin that is suposed to be hooked to the HD sensor
Its pin 9 of the controller. It is hardwired to ground and should be in the open to put it to DD.

I have edited this post too much

Anyway I don't get this opa opb part yet. What does the turbo-R need this pin 2 for. Just for DC right?? so no need to connect it to anything but disk change?

Par luppie

Paladin (869)

27-02-2014, 15:10

Hmmm, thats interesting. I still have my new drives lying around.
Thank you for ruining my evening, now I have to test it

Par Daemos

Prophet (2169)

27-02-2014, 16:35

you're welcome luppie

Still. Do you happen to know if pin2 only needs to be connected to DC?

Par luppie

Paladin (869)

27-02-2014, 16:46

Pin 2 on the drive needs to be jumpered to DC and connected to the DiskChange signal of the MSX (pin 24)
If you like I can do some measuring on my working (older) samsung drive what the state is of pin 9 of the controller.

Par Daemos

Prophet (2169)

27-02-2014, 16:51

Quote:

If you like I can do some measuring on my working (older) samsung drive what the state is of pin 9 of the controller.

yes please! Lets reverse engineer that controller. Many turboR users may profit from this little research.

Quote:

Pin 2 on the drive needs to be jumpered to DC and connected to the DiskChange signal of the MSX (pin 24)

So if I get your awnser right. All pin 2 needs to connect to in the FDD is to the Disk change signal which connects to pin 26 of the controller?

Par luppie

Paladin (869)

27-02-2014, 16:55

Daemos wrote:

Quote:

If you like I can do some measuring on my working (older) samsung drive what the state is of pin 9 of the controller.

yes please! Lets reverse engineer that controller. Many turboR users may profit from this little research.

Quote:

Pin 2 on the drive needs to be jumpered to DC and connected to the DiskChange signal of the MSX (pin 24)

So if I get your awnser right. All pin 2 needs to connect to in the FDD is to the Disk change signal which connects to pin 26 of the controller?

Yep
Controller pin 25 = RDY = Drive pin 34 = MSX pin 6
Controller pin 26 = DC = Drive pin 2 = MSX pin 24

That is the way to get both signals on a Samsung drive to make it compatible with the Panasonic MSX's

Par Daemos

Prophet (2169)

27-02-2014, 17:09

nice. I am missing Drive select 0 and motor enable 0 connections... However when I look at the photos no matter what you do all connections are led to:

drive select 0 and 1 go to pin 39 on the controller
motor enable 0 and 1 go to pin 38 on the contoller

Perhaps this disk drive only discriminates A or B mode through its pinout on the flatcable.

Par luppie

Paladin (869)

27-02-2014, 20:54

I tested it on a working (older) samsung drive. Pin 9 on the controller is 5V, so putting it high should select DD.

You are right about the flatcable. Modern drives use a solderpoint to route DS0/DS1 and ME to the same pins on the controller.

Par Daemos

Prophet (2169)

27-02-2014, 21:45

Thank you very much Luppie. I will test the modifications on this drive on a real turboR. If it works Ill let you know the details and take some photos. Some interesting material for your website?