3mode floppy drive

[genocho]

Yes, this post is about 3mode floppy drive in non japanese pc´s.

I know many pc bios have the option to configure 3,5 normal drives to 3mode, so with this feature activated, and the proper software, like raw-write, xfloppy, or winimage, we can make usable 3,5 floppies to use in x68000 compact machines.



I´m correct, or we need a real 3mode floppy drive appart to activate 3mode option in pc bios ?

I think, this can solve the problem of use real 3,5 backup disks on compact machines. It´s a format issue and how the data is writed to the disk, because 3,5 compact disks are formatted at 1,2mb and writed with special mode (3mode).

I think 3mode is only that, 1,2mb 3,5 floppy, and this in modern pc´s can´t be done because windows xp didn´t support floppy drives. Perhaps i´m wrong, anyway, it must be great if anyone can test to use a pc with 3mode feature activated and copy a 3,5 disk like 5 1/4 one.

Xflopy runs perfect if you have 5 1/4 drives, so why not 3,5 1,2mb disks ?

Anyone try it ?

Hope we can discover one of the greatest problems of preserve x68000 machines, to copy and use 3,5 drives with all 5 1/4 avalaible software.

The other "big problem" is adapt normal floppy drives for use when the original ones pass away.

Regards.

[genocho]

I found this:

http://articulo.mercadolibre.com.co/MCO-6902656-samsung-sfd-321u-144mb-external-usb-floppy-drive-_JM

It´s a samsung usb 3mode drive. Perhaps this floppy drive or equivalent, can be used in a non japanese pc to make right copies of 5 1/4 disks to 3,5.

The doubt is, this usb drive runs if activate 3mode bios support ? or not is neccesary for be an usb drive ?

Perhaps runs, perhaps not.

More data to investigate.

Hope something can make, working run copies of 3,5 disks with a normal pc.

Regards.

[NFG]

You must have a 3-mode floppy drive.  Enabling 3-mode support in the BIOS does nothing unless your drive also supports it.  Both sides (BIOS and drive) coordinate their actions.

[genocho]

Ok lawrence.

So with bios and 3-mode floppy drive. The only thing you need is win98 and xfloppy. Then I assume the process to make a bootable perfect copy is the same as you have a 5 1/4 drive, is it ?

Hope anyone can confirm this and test it with photos of the process.

The other mistery is to know what is exactly a 3-mode floppy drive appart 1,2mb 3,5 disk. The data is writed at low rotation speed of the drive ? The data is writed at different fat modes ? Why this people used this rare format with floppy drives ? ............. Why japanese machines are so special  ?

Lawrence hope you can connect a standard external or internal floppy 5 1/4 drive to a compact or other model , or a 3 1/2 one. I think can be possible, but how is the big deal.

We keep investigating about that.

Regards.

[genocho]

Hi again.

More info about 3-mode drives, in this case how to convert an standard pc floppy drive to 3-mode drive.
Perhaps this mod works with more drives, because it looks pretty easy, only need to solder pads in the floppy pcb.

http://majzel.blogspot.com/2009/04/converting-from-8-to-35-inch-floppy.html

The floppy drive used is samsung sfd 321b. This floppy drive is common in any pc outside japan (or in japan too).

One interesting thing i read in the article is that floppy drive in 3-mode spins at 360 rpm, that explain why 3,5 compact x68000 disks can´t be cloned with a normal 1,44 floppy drive (the data is writed at other rotation speed 300 rpm in mode standard).
This kind of floppy drives, perhaps can be used to replace 5 1/4 ones in real x68000 machines, the "only" problem is to wiring it properly, because with the modification it works like a 5 1/4 drives.



This is the pdf of samsung sfd 321b drive, for further information about the drive:

http://www.techtravels.org/amiga/SAMSUNG-SFD321B-070103.pdf

Well, if anyone have a pc that supports 3-mode in bios, and have a samsung sfd 321b, with a little modification of solder
opa1 contacts together, perhaps we can make perfect clones of 3,5 x68000 disks. I think no need to change ready signal or force format to low like this photo, anyway you can probe / error if not run with only solder opa1 contacts.



DS0 : Activate Drive Select 0 line
DS1 : Activate Drive Select 1 line

DC    : Activate Disk Change Signal
RDY : Activate Ready Signal

OPA For 3 Mode usage  (this is the pads must be solder together, see photo)
OPB (*1) For 1.6MB usage

(*1) Both "OPA" and "OPB" open : 2 Mode (1MB / 2MB)
"OPB" is connected and "OPA" is open : 2 Mode (1MB / 1.6MB)
"OPA" is connected and "OPB" is open : 3 Mode (1MB / 1.6MB / 2MB)

Hope something can test it and confirm that runs.

Regards.

[l_oliveira]

This kind of  "change" was used in a slightly different fashion in Brazil with 720 KB floppies to allow people with high density 5.1/4 drives simulate 3.1/2 inch drives in MSX computers.
I only figured out it was related to this 3-mode thing because you mentioned the trick is about the drive speed.

[TheRogue]

Just about all floppy drives from Y-E Data (many are re-branded, mine was sold as the Sony Vaio PCGA-UFD5) are capable of 3-mode, so says this site http://www.yedata.com/multi/4xslim.html .  Near as I can tell, just about all usb floppy drives are capable of 3-mode, it's just something that's pretty common these days.