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Full-height Tandon 5.25" and generic 3.5" floppy drive on the same cable?

Fire-Flare

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As the title says, I'm trying to get a Tandon full-height floppy drive to "play nice" on the same cable as a 3.5" drive.

I've tried setting the Tandon to Drive 0 and Drive 1 on the jumpers and removing the terminator block (and switching the other drive's position accordingly) but each time I boot the machine I get a "Floppy Error" message.


If somebody could show me how they got their Tandon to work with a 3.5" drive I would be grateful.
 
Could you provide information about what system you placing the two drives in? What controller are you using?
 
Could you provide information about what system you placing the two drives in? What controller are you using?

It's a custom build using an Axiomtek 86807 motherboard (made in 2003 I think), the controller is integrated into the chipset. (Intel 852GM + ICH*4)

The board supports dual floppies in 3.5" and 5.25" formats.
 
Right. Not exactly the system I was expecting nor one I am familiar with.

What power supply? The Tandon needs 900 milliamp on the 12v and 600 milliamp on the 5v which could be a noticeable draw for a tiny system power supply.
Did you ground the Tandon?
 
You need a floppy cable with the appropriate "twist" in it and, of course, a 34-position female edge connector. Set both drives to the second drive select (maybe labeled DS1, if the first is labeled DS0). The Tandon should probably have the terminator installed.
 
Right. Not exactly the system I was expecting nor one I am familiar with.

What power supply? The Tandon needs 900 milliamp on the 12v and 600 milliamp on the 5v which could be a noticeable draw for a tiny system power supply.
Did you ground the Tandon?

The power supply meets those requirements and the drive is grounded.


You need a floppy cable with the appropriate "twist" in it and, of course, a 34-position female edge connector. Set both drives to the second drive select (maybe labeled DS1, if the first is labeled DS0). The Tandon should probably have the terminator installed.

My cable has the twist and one of each connector in both positions, but none of the 3.5" drives in my possession have jumpers...
 
The 3.5" drive is probably internally set to DS1. That's the rule for most of the jumperless ones.

Do you know how to use DOS DEBUG? We can do a few tests. Reading the motherboard manual, it's not entirely clear that there's support for 2 drives there.
 
A lot of early full height 5.25" minifloppy drives do not drive a ready line.

The 3.5" minifloppy will drive the ready line.

I would think that the error is because the Tandon is not ready, and since the computer's floppy controller cannot detect a ready signal from the Tandon, it generates a disk drive error.
 
A lot of early full height 5.25" minifloppy drives do not drive a ready line.

The 3.5" minifloppy will drive the ready line.

I would think that the error is because the Tandon is not ready, and since the computer's floppy controller cannot detect a ready signal from the Tandon, it generates a disk drive error.

Why on earth would you want a READ/ line on a Mini-ITX P4 board? It doesn't use READY/--it expects either nothing or DISK CHANGED/ on pin 34, which from the sounds of the drive not even having DS jumpers, is a HD drive with pin 34=DC.

And why would this require a drive set to DS0?

Standard PC AT-type cabling, folks. My suspicion is that the second floppy isn't actually implemented in hardware traces. It wouldn't be unusual for a mini ITX board of this vintage. The user's manual for the board is suspiciously silent on this and only talks about the BIOS setting--and that may be pure boilerplate and not reflect reality.
 
For whatever it is worth, a while back I did have a Tandon full height 360k drive connected to a ~2000 era motherboard (KT7A AMD Athlon XP) and it did "work", although I ran in to some other odd problems where inner tracks would give random read/write errors even though the drive worked perfectly elsewhere. Never got to the bottom of that, and it seemed specific to that system.

Anyway, in theory this should work if your motherboard actually does support two drives and has proper 360k support in the BIOS. The drive jumpers/switches will need to be set as a "secondary" drive. You will need to set the drive types in the BIOS.

The lack of a Ready/changed line (as most 360k drives lacked) would probably only cause issues on a system that only recognizes 1.44mb or 1.2mb drive types.

If the BIOS or chipset does not really support two drives, then you would have to connect it to the "A" plug on the twisted cable and you would not be able to use a second drive in conjunction.

The thing though is that in either of those two cases, plugging a 360k drive configured as "B", your computer should still boot fine, you just won't be able to access the a B: drive.

A couple of questions: Are you trying to boot from the 3.5" floppy or a hard disk? What model of Tandon drive is this? (TM 100-2A?) Does your BIOS setup have selectable settings for 1.44/1.2mb/720k/360k and for both A: and B: drives? Are your BIOS setup drive types set correctly (1.44mb as A and 360k as B)? Does your 3.5" drive work by itself when the Tandon is not plugged in? Does the "Floppy Error" occur before or after it tries to boot an OS?
 
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My suspicion is that the second floppy isn't actually implemented in hardware traces. It wouldn't be unusual for a mini ITX board of this vintage. The user's manual for the board is suspiciously silent on this and only talks about the BIOS setting--and that may be pure boilerplate and not reflect reality.

I'm confident that the board does support dual floppies, that's why I ordered it.

I can configure drive A and B's size and capacity in the BIOS and Windows 7 shows both in My Computer.
 
A couple of questions: Are you trying to boot from the 3.5" floppy or a hard disk? What model of Tandon drive is this? (TM 100-2A?) Does your BIOS setup have selectable settings for 1.44/1.2mb/720k/360k and for both A: and B: drives? Are your BIOS setup drive types set correctly (1.44mb as A and 360k as B)? Does your 3.5" drive work by itself when the Tandon is not plugged in? Does the "Floppy Error" occur before or after it tries to boot an OS?

Hard disk for now, I'd like to install Windows 3.11 later.

I'm not certain, I'll pull it out later and look. (Edit: Yes, it's a TM100-2A)

Yes, the BIOS supports all of those.

Yes, I double-checked.

Yes, the 3.5" drive works solo.

The "Floppy Error" occurs at the end of the POST routine, It's set to "Halt on all errors."
 
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I'm confident that the board does support dual floppies, that's why I ordered it.

I can configure drive A and B's size and capacity in the BIOS and Windows 7 shows both in My Computer.

Okay, let's assume that there's complete support. Some questions, now.

1) If the 5.25" Tandon is set up as drive A: with no 3.5" connected, does it work?
2) If the answer to (1) is "no", what's the state of the floppy LED during POST? Always on? Never on? Only on during accesses?
3) Does the spindle motor come on when the floppy is accessed, or is it always on?
 
Okay, let's assume that there's complete support. Some questions, now.

1) If the 5.25" Tandon is set up as drive A: with no 3.5" connected, does it work?
2) If the answer to (1) is "no", what's the state of the floppy LED during POST? Always on? Never on? Only on during accesses?
3) Does the spindle motor come on when the floppy is accessed, or is it always on?

When connected solo as drive A, the machine boots with no errors and the motor and LED activate only when the drive is accessed.

However, when I try to access the drive in Windows, I still get a pop-up that says A:\ is not accessible due to a device I/O error.

Windows is aware that it's not a 3.5" drive, the icon shows a 5.25" disk.
 
Perhaps we've stumbled on something. Let's leave the 5.25" as the only (A:) drive for now.

Boot DOS or shutdown Windows to DOS (that's not the same as opening a DOS window). I don't recall what version of Windows you're running; if it's 3.0/3.1, just don't load Windows and stay at the DOS prompt.

Run FORMAT A: /F:360 /u with a scratch 5.25" DSDD disk in the drive. Depending on the version of DOS, [/b]/u[/b] may not be supported--if that's the case, leave it off.

Let's see if we can format a disk at the lowest possible level.

Oh--and for this test involving a single drive you need to have the terminator DIP installed on the Tandon drive.
 
Perhaps we've stumbled on something. Let's leave the 5.25" as the only (A:) drive for now.

Boot DOS or shutdown Windows to DOS (that's not the same as opening a DOS window). I don't recall what version of Windows you're running; if it's 3.0/3.1, just don't load Windows and stay at the DOS prompt.

Run FORMAT A: /F:360 /u with a scratch 5.25" DSDD disk in the drive. Depending on the version of DOS, [/b]/u[/b] may not be supported--if that's the case, leave it off.

Let's see if we can format a disk at the lowest possible level.

Oh--and for this test involving a single drive you need to have the terminator DIP installed on the Tandon drive.

I may have stumbled across something as well. I tried a half-height 360kb drive in the system and it's booting properly but not accessible in Windows 7 either.

Perhaps Windows 7 is the problem and doesn't support 360kb drives? (My Google searches won't give me a straight answer)


I'm going to try installing Windows 3.1 from the 3.5" drive and see what happens in there.
 
I can say that 360K is supported in XP, but have never tried in Win7. Wouldn't surprise me, though. Heck it wouldn't surprise me if floppy support was eliminated completely in W10.

I'll add that if you're doing this exercise for creating and archiving vintage floppies, Win7 is not what you want. Try Win98SE, for example. You should be able to run DOS utilities such as ImageDisk there.
 
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Haven't tried it myself, but from what I have read Windows 7 does not support 360k drives. Windows 10 does still have some floppy support, at least it recognizes emulated 1.44mb floppies in VirtualBox.

Is this Tandon drive known to work in some other system?
 
Windows 10 does still have some floppy support, at least it recognizes emulated 1.44mb floppies in VirtualBox.

Not the same thing at all; VirtualBox is creating the hardware environment. Virtual floppies are, after all, just files.
 
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