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3mode floppy drive

Started by genocho, August 24, 2009, 11:17:52 AM

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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.



I found this:

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.



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.


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  ;D ?

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.



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.

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:

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.



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.


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 .  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.
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