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Formatting HD Floppies as 800K?


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I can't seem to get a floppy that both my plus and my SE like. All I have are HD disks. If I format it on the plus as a double-sided disk, I get (as expected) an 800K disk that the plus likes just fine. But, when I put it in the SE, it doesn't like it, and asks me if I want to format it.

 

Am I doing something wrong? All I have are HD disks, but I thought they could be formatted as 800k disks. What do I have to do to get a floppy that both machines like?

 

Thanks,

Nathan

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The tape hack is a bit of a hit-or-miss affair. It works best if the disk has *never* been formatted as 1.4MB (or if it has otherwise been erased with a degausser). The write field of an 800K drive is a bit on the low side, relative to that in a 1.4MB drive, so an 800K drive may not reliably overwrite any data previously written by a 1.4MB drive. Add a small amount of track misalignment between drives, and you can quickly eat up any margin that might have existed. Even if things seem to work, that may be a temporary state of affairs. The tape trick should therefore be reserved for emergencies.

 

Since the media used in 720K PC disks is exactly the same as that for 800K disks, just hunt down some of those. It's a lot easier, and you'll have much less trouble. Many office supply stores have stopped stocking them on their shelves, but will happily order them from their warehouse for you. And there are still many online stores that stock them cheaply.

 

Too bad you don't live near silicon valley. I've got about a trillion of these I'd happily give you.

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Unless you enjoy the pain of floppies, why not forget them. You have two serial ports at your disposal. One cable, a one-time fiddle to set up, and "Bye bye, floppies". The SE is just a tarted-up Plus, so there should be no hiatus between them but for the DB-9/miniDIN-8 cable procurement.

 

de

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Plenty of people have reported that this works (for a time), so to declare that it never works is simply incorrect. I've used this hack myself with short-term success.

 

As I posted, you can still order the right disks online. And as of a year ago, Office Depot offered them as a special-order item, for instance.

 

Absent that, another option is to degauss a 1.4MB floppy before using the tape hack. That worked wonders to increase yields for me. But again, this was only for a short term. I would never trust this trick to work over the long term.

 

But as equill said, there are ways to bypass this hassle altogether.

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I've heard that it is best to use opaque tape or electrical tape when tapeing the hole in a 1.4MB floppy. Apparantly some Macs use optical sensors to check for 800K/1.4MB disks and clear tape won't block out the light. I used to use this trick with my Plus and it worked alright in most cases. However I was lucky enough to get a big box of 720K floppies for free so I use those now.

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I hate to be the party pooper here and ruin the fun, but being an 18 year computer veteran who has seen this happen unsuccessfully all too often, I must bear the bad news.

 

You should NEVER format a 1.4MB as an 800K. The media itself is different and even if it works for a while you'll run into problems because a 1.4MB floppy wasn't designed to work as an 800K.

 

The same logic applies to using an 800K as a 1.4MB. The media is different!!!

 

You CAN use 400K and 800K interchangeably, but if you have a disk you've used as a 400K for more than a few years in only 400K drives don't use it as an 800K. The pads on 400K drives will wear out that side a bit.

 

As for finding 800K disks, here is a link to purchase Imation disks...the picture is wrong but the specs are right:

http://www.superwarehouse.com/Imation_3.5_DS_DD_Floppy_(10_pk)/12882/p/46719

 

I recommend you get NIB disks and not some guy's old floppies that he's been using since 1990.

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Unless you enjoy the pain of floppies, why not forget them. You have two serial ports at your disposal. One cable, a one-time fiddle to set up, and "Bye bye, floppies". The SE is just a tarted-up Plus, so there should be no hiatus between them but for the DB-9/miniDIN-8 cable procurement.

 

de

 

Mmm, no I don't enjoy floppies. Less and less than before. Appletalk will happen, but I still need an 800k disk to boot the plus. This thread has convinced me to just order a box online :)

 

My goal is to get one 800k floppy with system 6 and ethertalk booting my plus so I can have a silent (fanless) mpd client sitting in my breakfast nook.

 

Nathan

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I hate to be the party pooper here and ruin the fun, but being an 18 year computer veteran who has seen this happen unsuccessfully all too often, I must bear the bad news.

 

You should NEVER format a 1.4MB as an 800K. The media itself is different and even if it works for a while you'll run into problems because a 1.4MB floppy wasn't designed to work as an 800K.

 

No disagreement that it's a bad long-term idea (as I've already stated). But absolutes like "NEVER" are hard to defend. Emergencies do arise, and for those, it's SOMETIMES okay.

 

How can this work? First, the media properties are not as different as you seem to think. The coercivities are within 10-20% of each other (e.g., 650 vs 720 Oe), and the active-layer thicknesses are not significantly different, either. These differences, in fact, are about the same as the variation from vendor to vendor, and over temperature, to say nothing of the variation in write fields produced by a random assortment of drives. So, it can work ok (notice that I don't assert that it WILL work ok; I try to choose my language carefully). The recommendation I mentioned -- that you use only virgin floppies (and proper degaussing is a good "revirgination" process) -- greatly enhances the chances of success, allowing you to get up and running in a pinch. If all you need is to get an OS onto a hard drive, this can be a lifesaver (I've done this several times, so I'm not speaking theoretically). If you're expecting the floppy to retain that data reliably beyond that time, you've got high hopes.

 

Going the other way -- using an 800K as a 1.4MB disk by cutting/drilling/melting a second hole -- similarly CAN work, but is inadvisable for anything but a short-term emergency hack. And again, should it work once by some miracle, be happy with that luck, and don't expect anything more.

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Yes, it may work in a pinch for short-term solutions, but I don't advise it. I tried an experiment with a 1.4MB disk in March 1995. I formatted it as 800K (with a Plus) and stuck a few Kid Pix documents on it. I used it in two different Macs--an SE SuperDrive and an LC--and after about six days of being accessed about three-four times daily it conked out.

 

The disk was pretty messed up--I couldn't reformat it as a 1.4MB--it said it was damaged. Your mileage may vary, but that's my story.

 

There's a good section in the older editions of Mac Secrets on this topic.

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Yes, it may work in a pinch for short-term solutions, but I don't advise it. I tried an experiment with a 1.4MB disk in March 1995. I formatted it as 800K (with a Plus) and stuck a few Kid Pix documents on it. I used it in two different Macs--an SE SuperDrive and an LC--and after about six days of being accessed about three-four times daily it conked out.

 

The disk was pretty messed up--I couldn't reformat it as a 1.4MB--it said it was damaged. Your mileage may vary, but that's my story.

 

There's a good section in the older editions of Mac Secrets on this topic.

 

Please carefully re-read what I wrote. Whether or not you "advise it" is -ahem- quite beside the point. Your own data support that it can work for a short time, and that's all you need to take care of an emergency. I'm not quite sure why you seem to be taking such a zealously negative position. Just give folks the facts and let them run with them, I say. They're not infants.

 

Reading Mac Secrets' discussion on the topic is unlikely to be further enlightening. With due respect to the authors of that tome, I doubt they can add anything to the points I've made, viz:

 

1) It's unreliable in the long term.

2) It can work in the short term (and there are definite steps one can take to increase the short term reliability)

3) If you understand and acknowledge 1) and 2), and live within the limitations implied therein, then there's no problem.

 

Btw, your "messed up" disk could've been revived easily with a good degaussing. I've run many experiments because I was curious why the reliability was poor. Identifying the quantitative differences between the media suggested that degaussing would materially improve reliability. Experimentation verified the correctness of the hypothesis.

 

I'm not exactly clear on the relevance of March 1995, but while we're exchanging random data, my first experiments were run around Arbor Day in 1990. :)

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