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Hard sector floppy disks - 5.25", 10 sector, 96TPI, double sided

1

1980s_john

Experienced Member
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Apr 29, 2005
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365
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Hi,

I have an eBay auction running for 1 disk, see http://www.ebay.com and search for item 330471931462.

I have a Northstar Advantage that uses 48TPI hard sector floppies, these disks will obviously work fine on it, but which machines need 96TPI (80 or possibly 77 tracks)? The only example I have found so far is a Heath H8 with H17 drive using an 80 track drive, but there must be others.

Regards,
John
 
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It doesn't matter--floppies labeled 96 or 100 tpi differ from 48 tpi only in that they have been verified at the higher track density. Physically, they're the same and will work in either type of drive.
 
I'm a bit of a dummy, but... Are these the ones that could be used with, say, a Tandy TRS-80 Model 2000?

Though I don't believe the quad density ones used in the Tandy are hard sectored...
 
No--a hard-sector floppy (8" or 5.25") has multiple holes punched in the cookie at equal intervals--and then an extra hole signifying the index midway between two of the sector holes. You can tell one by rotating the cookie inside the jacket and seeing the multiple holes go by the index aperture. Not common in 5.25" (although some early word processors used them) and pretty much disappeared by the time the 5150 came out.

Some 8" drives (e.g. Siemens FDD100/200) can be jumpered to separate index from sector holes onboard the drive, so that the drive can use either hard or soft-sectored media as soft-sectored.
 
EddieDX4 said:
I'm a bit of a dummy, but... Are these the ones that could be used with, say, a Tandy TRS-80 Model 2000?

Though I don't believe the quad density ones used in the Tandy are hard sectored...
Click to expand...

I have a box of BRAND NEW (were shrinkwrapped, I opened at one point but all disks are still in sleeves in box, unused) Athana-brand quad-density 5.25" disks that you might be interested in...

I might be able to secure another box, if you're in need of more than one box - other box may be shrinkwrapped still, dunno, a friend had it.
 
Raven said:
I have a box of BRAND NEW (were shrinkwrapped, I opened at one point but all disks are still in sleeves in box, unused) Athana-brand quad-density 5.25" disks that you might be interested in...

I might be able to secure another box, if you're in need of more than one box - other box may be shrinkwrapped still, dunno, a friend had it.
Click to expand...

Quad-density is really pointless. Most used ordinary double-density floppies. I got really curious about this back in the 80s, so I asked my friend over at Dysan for the skinny.

He replied that in the early days of 5.25" media, yields weren't spectacular. So media was verified for 96/100 tpi double-sided; if it failed, it was passed to the 48 tpi verifier and if a cookie failed, it was branded as sigle-sided and "flipped" in the jacket so that the "good" side was used. As yields improved, the single/double sided selection was dropped and then the quad/double-density testing went the same way. He noted that Dysan still offered disks branded as "quad density" and observed that at one time, they'd even differentiated between 96 and 100 tpi--but mostly, it was a branding issue, not a testing one.

FWIW, the media itself is identical in every physical and magnetic respect.

As an aside, one cannot make the "physical" claim for single- and double-sided 8" floppies--they differ in where the index aperture is placed in the jacket. Some drives have two sensors to accommodate both types of media.
 
Without a special driver (to perform double-stepping) , you're not going to use it as a 360K drive.

These were used on some CP/M systems as well as oddballs such as the DG/One. Electrically, they're no different from 3.5" 720K drives--if your BIOS supports the configuration, you can simply declare it as a 720K drive.

But why bother? You can buy a Teac FD55GF "1.2M" drive and jumper it to behave just like this drive.

BTW, do you get the pattern in Teac's drive suffixes? B = 360K, F = 720K G = 1.2M H = 1.44M. So an FD235HF is a 3.5" drive that supports both 720K and 1.44M; a FD55GF supports 1.2M and 720K. A FD235HG supports 1.44M, 1.2M and 720K (implied, not explicitly stated). A FD55B is a 360K 5.25". You'll occasionally see an "A" drive, which is single-sided and a "J" drive, which is 2.88M.
 
Chuck(G) said:
Without a special driver (to perform double-stepping) , you're not going to use it as a 360K drive.

These were used on some CP/M systems as well as oddballs such as the DG/One. Electrically, they're no different from 3.5" 720K drives--if your BIOS supports the configuration, you can simply declare it as a 720K drive.

But why bother? You can buy a Teac FD55GF "1.2M" drive and jumper it to behave just like this drive.

BTW, do you get the pattern in Teac's drive suffixes? B = 360K, F = 720K G = 1.2M H = 1.44M. So an FD235HF is a 3.5" drive that supports both 720K and 1.44M; a FD55GF supports 1.2M and 720K. A FD235HG supports 1.44M, 1.2M and 720K (implied, not explicitly stated). A FD55B is a 360K 5.25". You'll occasionally see an "A" drive, which is single-sided and a "J" drive, which is 2.88M.
Click to expand...

You're a walking (or should that be "typing") encyclopedia... Thank you!

The only reason I am interested is for building floppies from images for my Model 2000.
 
Chuck(G) said:
BTW, do you get the pattern in Teac's drive suffixes? B = 360K, F = 720K G = 1.2M H = 1.44M. So an FD235HF is a 3.5" drive that supports both 720K and 1.44M; a FD55GF supports 1.2M and 720K. A FD235HG supports 1.44M, 1.2M and 720K (implied, not explicitly stated). A FD55B is a 360K 5.25". You'll occasionally see an "A" drive, which is single-sided and a "J" drive, which is 2.88M.
Click to expand...

This I did not know - useful.
 
Actually, there is a way to make a quick mod on one of the boards in the TEAC FD-55F to make it double-step automatically, so it can easily be used as a 360K drive. The mod can be done as a permanent change or be made switchable using an external SPST switch. I had to hunt this one down for a friend a couple of months ago. I'll check to see if I still have the procedure and the page from the TEAC drive manual that shows the affected portion of the board. I bought four of these from this EBAY seller a few months ago--they do great packing and the price is, as noted, more than reasonable.
 
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