Format 1.2 mb HD disks to 500 kb for atari 800xl

[Dripfree]

So I got a bunch of 1.2 mb high density disks. I keep stumbling across them at thrift stores. I want to format them to 500 kb so I can use them on my Atari. I know this is not recommended because they can be unreliable. That does not concern me because I have an SIO2PC. The thing is with my setup it's actually easier for me to load from my 1050. So I want to get some stuff on these disks if it does fail over time ill just put it back on again. Problem is I can't seem to figure out how to format them down to the lower density. I've tried a few different DOS'es and they all seem to give me some type of error. I even tried formating to the lower density on an old PC with no luck. I think it's got to be possible because I found a lot of places recommending against it, but no where that tells how to do it. If anyone knows how to do this some instructions and pointers would be greatly appreciated.

[+bob1200xl]

It can't be done on properly functioning hardware. The only way you are going to be able to use such disks is on a drive set up for 1.2mb - controller and all. Keep looking for SD/DD disks.

 

Bob

[Dripfree]

Thanks for the quick response Bob I didn't realize that. I had just done a general search for info on this and I guess what I read wasn't Atari specific. Too bad cuz I got a bunch of these disks. I got an old PC I'll use them on but it just doesn't see the action that my Atari does.

[Osgeld]

Even if you can its sometimes funky, someone told me the reasoning behind it but it sounded like a best guess, and it may depend on how the machine handles its floppies, but I do know I have tried it in the past with less than spectacular results on pc and mac

 

it may be good enough to get something done but it doesnt last long

Edited September 2, 2013 by Osgeld

[Marius]

It's the used material, and it's BIAS that makes that it fails (eventually). Sometimes it fails after a usable time, but sometimes it already fails right after the write operation.

[1050]

Most high density disks are failing between format write and verify passes so that you can't even get them formatted. Every time here, but perhaps someone got one to format and pass muster somewhere? Not at all like the 720K and 1.4 meg issue with 3.5 floppies, those are the ones that can fail data reads after days and days. Same issues, different media, head width, and bias levels yet again.

[Marius]

@1050

 

The issue with the 3.5" disks 720/1.44 failing data is the same as with the HD 5.25" disks.

 

I have HD 5.25" disks which work great... For a while.

[+Larry]

There is a little caveat to this story. The oxide formulations that various mfg's used over the years varied quite a bit. Some (probably extremely few) were very similar to the DD formulations. I have some 3.5 HD disks used as DD that were stable for years. Still, the odds of walking into a thrift store and getting "compatible disks" are "slim to none." And since the "real deal" is still available, HD for DD is still a bad idea.

 

-Larry

[RodCastler]

One thing you may want to try is a magnet.

 

Back in the day I'd paint throughout the surface of the diskette's plastic carrier with a strong magnet. That would allow me to successfully format and then use those diskettes on my 1050.

 

I've done it again today using a magnet taken from a hard drive, which is way stronger than what I could afford back then but it also works. I remember these were fairly reliable after the treatment.

[+Larry]

One other possible "fix" for Dos 2.0s is BURP -- a utility from the early Analog mags (maybe #8?) and probably in the Analog Compendium. It will mark the bad sectors out in the VTOC and make the disk usable. However, it was never written for an application like this -- just an occasional sector that would not format properly. But maybe worth a try?

 

-Larry