Disks for 9114B ?



#2

I have I hope just bought one !

What kind of disks should I use ?

Sean


#3

Double-sided double-density (not "high-density"). The kind that are called 720K when used in PCs, or 800K when used in old Macs.


#4

Just to add a couple of details that may help to spot them: IIRC, such floppies have 80 tracks, and the radial density is 135 tpi (tracks per inch). For PC (MS-DOS) usage, they are formatted with 9 sectors per track. They were also used in Amiga 1000 and Amiga 500 computers, but with a proprietary format. And also were used in some MSX and other computers around 1986.

PC: 720 KBy

Macintosh: 800 KBy

Amiga: 880 KBy

#5

I may still have a few of them lying around. If I do, I would be happy to send them to you.

#6

In a pinch you can tape over the hole on a 1.44 and use that. I have had no problems doing that, however I prefer to use 720k disks. You can get them from floppydisks.com. They have great return policies.


#7

The "currently standard" 3.5" floppies, which are usually formated at 1.44 MBy and marked as HD (High Density) instead of DD (Double Density), should be useable (I don't have a 9114 to check by myself). You may wish to tape the square hole opposite to the write-protect tab, because that hole is what "tells" the drive that it's a HD and not a DD floppy.

As HD and DD both have 80 tracks, HD should work with no problem. In the PC world, DD are formatted with 9 sectors per track, and HD with 18 sectors per track, here is where the capacity increase comes from. Be sure to reformat the disks before usage.

A different case was the one concerning 5.25" floppies, where the higher density disks (1.2 Mby) had 80 tracks while standard disks had 40 tracks. The narrow tracks of the "larger" disks created many alignment issues and read errors at those times.


#8

The big problem with using 5.25" HD media as standard density (DD) is that the coercivity of the media is MUCH different (600 vs. 300 Oe). It was entirely unreliable to use HD as DD or vice versa, even if you were using the same track pitch. Writing to HD media on a DD drive usually wouldn't result in data that could be read back again reliably on any drive.

With 3.5" disks, the coercivity of HD and DD media is much closer, 750 vs. 600 Oe if memory serves. That's close enough that a DD drive can write to the HD media, though the error rate is measurably higher and the long-term reliability is probably reduced.

If I had some kind of emergency where I needed a 3.5" disk to use in a DD drive (like the 9114), and all I had were 3.5" HD disks, I'd cover the hole and use one, but I wouldn't ever do that as general practice. DD disks just aren't that hard to get.

Stock up now, though. In a few more years it will become difficult and expensive to get either DD or HD disks.


#9

I fully agree with previous comments: By all means try to use DD disks.

You can use HD instead just as "emergency" media, but get DD's as soos as you can...

However, what I can't figure out is how could HP (or SONY which is the actual manufacturer of the drive inside a 9114B) place a "media desity detection switch" into a drive... years before HD media become available? ;-)

Ok, (couldn't resist) a long way to say that there is no such switch into 9114 drives, so no need to tape the hole... just insert your disk and try formatting!

Cheers

Diego.


#10

IIRC, the switch in the DD drive was intended as a "media present" detector. If you insert HD media, it doesn't think there's any media present.

HD drives sense media present using a detector in a different position, so that they sense the presence of either DD or HD media. They have a separate sensor for the HD hole.


#11

Hi Eric,

That's true for the PC world... but 9114B has nothing to do with densities, DOS formats, etc. Its "media present" switch is placed in the same side where "write protection" is, but at the top of the disk, besides the sliding head window cover.

The only reason for taping the "media density hole" in an HD disk while dealing with LIF formats, is in the case that you need to use your disks in a DOS running old PC with LIF utilities.

This will allow the PC to accept the disk as a DD, and LIF to work as expected. But remember that reliability is compromised by this practice.

Hope this helps...

Diego.

#12

Quote:
Stock up now, though. In a few more years it will become difficult and expensive to get either DD or HD disks.

I've got some DD disks, too (15 or 20) that I would be happy to send to whoever can use them.

#13

Of course, Eric is right and more precise than me about the coercitivity issue.

I did some design with 3.5" floppy drives back in 1989 and also found important differences between similar units from different maunfacturers (IIRC, we were using mostly Fujitsu drives with our 64180-based data capture device). I think that the ability of a DD drive to write on HD media may also differ from one drive manufacturer to other. In my particular experience, HD media performed well when used in DD drives, but I cannot deny the chance for higher error rates that were perhaps masked by software or brute-force retries, and being not that apparent (at least for me). One funny thing that happened with some very slim drives we used in some units, was that a particular brand of diskettes seemed to require more rotational torque, and we detected many cases in which the specific combination of those drives and those disks, with some dirt added, resulted in more service calls than all other combinations.

Of course, sometimes we don't have all the brands and options available here, and also... while I enjoy recalling stories from the past, I realize my comment have gone way OT, so I apologize.

Edited: 7 May 2009, 8:18 p.m.


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