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5.25" floppy drive bible ?

marc.hull

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Need help here....
I have six or so 5.25" floppy drives that I have accumulated over the last while. They look good lining the wall but I'd like to get some use out of them. Problem is that info on these drives is hard to find (at least for me.) Surely there must be a clearing house that hosts info on the drives and their jumper settings Or at least a site with a pack rat's haul of data sheets? If there is I would appreciate a gentle nudge in that direction.
Thanks....

Marc.
 

marc.hull

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What drives are they? Maybe we can attack this piecemeal.

OK... Just remember that you asked ;-).


Mitsubishi 4853
Panasonic JU-455-7ACG
Mitsumi D503
Mitsubishi MF501A-362U
Mitsubishi MF504A-362U
Mitsubishi MF504B-362U

Thanks for helping Chuck.
 

SpidersWeb

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Mitsubishi 4853 -720Kb DSQD
Mitsubishi MF501A-362U - 360Kb DSDD
Mitsubishi MF504A-362U - 1.2Mb DSHD
Mitsubishi MF504B-362U - 1.2Mb DSHD
Mitsumi D503 - 360Kb DSDD
Panasonic - 99% sure it's 360Kb DSDD

I'd expect all have the standard jumpers. Only one you really need to check is "DS" or "Drive Select" - for normal PC use, you want this in the '2nd position' - might be DS1 (if the options are 0-3) or DS2 (if the options are DS1-4).

Just a start anywho :)
 
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Ole Juul

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Well, for the MItsubishi 504B, this this might help.

http://this ??

I wonder if the OP actually needs jumper details or just needs to figure out how to deal with the dd hd thing. I've generally found that 1/2 height units are already jumpered correctly and I just plug them in - the usage being what I need to understand.

Anyway, I have the 504 listed as dual speed, if that's of interest. Also, the JU-455 is indeed listed as 360. So now it is probably only needed to plug them in and set the bios. Hoping, of course, that somebody hasn't diddled the jumpers. :)
 

modem7

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Of course, sometimes one has to change jumpers from the default.
I have a JU-455-7, and for it to work in my IBM AT, I have to remove the RY jumper (disconnects pin 34 of connector from circuitry).

Presumably, that is tied in with the following text from Mueller in his Upgrading & Repairing PCs book:
"To recap, PC and XT systems do not care at all about pin 34, but AT systems need pin 34 set to Diskette Changeline (DC).
If the drive does not support the DC signal and you want to install it in an AT, pin 34 must be open but not set to Standard Ready (SR)
."
 

Great Hierophant

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Two quick questions :

An HD 5.25" drive spins at 360rpm, so why have a jumper for 300rpm? If set to 300, wouldn't that cause problems for all HD floppy disks? Does the higher speed cause any issues when reading or writing DD disks?

I understand that the Drive Change signal is present on IBM AT controllers, but is it to be found and used in all controllers that support HD floppies? I assume that virtually all HD 3.5" drives support it, but what about DD drives, which were often installed in PC/XT type systems?
 

Chuck(G)

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The jumper for 300 RPM can be keyed from pin 2 (density); a drive can be made to act as a 720K drive at the normal data rate of 250K, and still support the 500K HD rate without the need for a 300Kb/sec clock. There were some older third-party controllers that required that. The speed, assuming that you have a conforming controller, should not be an issue. Similarly, you should be able to get 1.44MB on a 5¼" HD drive spinning at 300 RPM.

The same obtains with 3½" drives. Normally 500Kb/sec data rate at 300 RPM, but NEC went with 360 RPM for their systems, so that in 8", 5¼" and 3½" drives all have the same logical format.

And there are 5¼" drives that do not support DD at all.

On 5¼" DD drives, most PC ignore DC; 720K 3½" drives can have it or not.
 

MikeS

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An HD 5.25" drive spins at 360rpm, so why have a jumper for 300rpm? If set to 300, wouldn't that cause problems for all HD floppy disks? Does the higher speed cause any issues when reading or writing DD disks?
That confused me too when I first ran across 5.25HD drives. As Chuck says it's the data transfer rate that matters in this context and not the RPM; another way of looking at it:

A DD drive spins at 300RPM and transfers data at 250kb/sec; an HD drive spins at 360RPM (6/5 x 300) so to read/write a DD disk we simply set the controller to read/write at 300kb/sec (6/5 X 250).

Of course the drive also has to change the signal strength to match the different magnetic characteristics of the diskettes and the controller has to double-step the DD disk's 48TPI vs. the HD's 96TPI.

Again as Chuck mentions, a 5.25HD drive spinning at 300RPM instead of 360 is useful if you want to use 96TPI 'QD' diskettes as used in many older non-PC compatibles and even sort-of compatibles like Toshiba T300s for example.

On the other hand, 3.5" drives spinning at 360RPM instead of 300 are useful for replacing 8" drives.
 
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Great Hierophant

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Does DOS 3.x and above support the drive change functionality of an AT controller? If it does, then I assume that floppy drive operations in general would be faster because DOS does not have to re-read the FAT every time the user type a command that affects the floppy drives.

So, the 300rpm jumper can be used to support a 720KB 5.25" disk format. I infer that because the data rate is 250KB/sec, it would work with a standard low density PC/XT controller. As it is laying 80 tracks, it requires the use of HD 5.25" floppy disks. Am I right here?
 

Chuck(G)

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No, double-density.

The problem with the "disk changed" issue is that one has to reset the signal by stepping the heads--and the drive may well not have a disk in it anyway. So, if you were on cylinder 0 and needed to be on cylinder 0 after a disk change, to reset the DC indication, you need to do two seeks--one track in, then one track out.
 

Great Hierophant

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It sounds like to me that you could "fool" DOS 3.2 and above into thinking it is accessing a 720KB 3.5" disk drive with an appropriate 5.25" HD floppy drive and double density media.
 

k2x4b524[

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any data on the CDC Magnetic Peripherals Model 9428-02. From what i remember, i may have asked here before. These are quad-density drives? 3 more just fell into my lap so now i've got 4 *sigh* The drives are stamped APR 18, 1984, lot number 8508, they've got an intel rom chip on it next to a big block of unmarked jumpers
 

krebizfan

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any data on the CDC Magnetic Peripherals Model 9428-02. From what i remember, i may have asked here before. These are quad-density drives? 3 more just fell into my lap so now i've got 4 *sigh* The drives are stamped APR 18, 1984, lot number 8508, they've got an intel rom chip on it next to a big block of unmarked jumpers

Bitsavers has a 9428 manual. You may want to check it to confirm nothing major got changed with the 9428-02 model. What information I have suggests that the 9428-2 was a DSDD (360kB) model with the 9428-1 being a single sided variant and 9429 being the quad density (720kB) variant. The good part about quad density drives is that they work fine as double density drives; it's those single sided models sold as 360kB drives that are the problem.
 

k2x4b524[

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Great, thanks for the pointers, i downloaded the pdf, and i'm almost sure its a ds-qd drive, i'll put up to my 5160 test setup and see for sure, the stepper motor label has 1.875 degree step rate faintly visible on it. Isn't that the step rate for a 1.2mb drive?
 
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