Single Densisty / DD / HD and "13 sector vs 16 Sector"

Ive had some problems burning some of the disk images from Asimov.net
Some of them won't work.

I'm not up on all this stuff yet, so a few questions:

-Why won't the HD disks work with Apple II?

-Whats the difference between the DISK II Controllers? 13 sector vs 16 sector?

-Does the older controller makes 13 sector disks, and a newer controller makes 16 sector disks?
-Could this be why some of the disk images wont work?

I have this controller installed:
http://www.apple2world.jp/apple2/COL/MapItems/card/img/disk2interface.jpg

I have ordered this controller:
http://ripsaw.cac.psu.edu/~mloewen/Oldtech/Apple/DiskController-1L.jpg

Also does anyone know the difference between Dos 3.3 and ProDos?
-Does Dos3.3 use 13 sectors and Prodos uses 16?

Cheers :)

Apple DOS 3.1 and 3.2 were 13 Sector, Apple DOS 3.3 was 16 Sector, as well as Apple ProDOS.

I didn't use UCSD Pascal, but IIRC, it's also 16 Sector.

I have used all kinds of NON High Density 5.25" disks in my Apple ][ Drives..

I believe the Density of Magnetic Material in the High Density Disks is too much for the Apple Drives to change, so they DO NOT Work...

You are asking for a lot of technical information. Here is a partial answer.

DOS 3.1 uses 13 sectors per track with 35 tracks per disk and 256 bytes per sector.
DOS 3.3 uses 16 sectors per track with 35 tracks per disk and 256 bytes per sector.
PRODOS uses 16 sectors per track.

DOS 3.3 can convert a 13 sector disk to a 16 sector disk.

DOS is sector based and PRODOS is block based (1 block = 2 sectors). There are other differences but this is the main core difference.

I am not 100% sure but early disk controllers might not handle 16 sector disks at the hardware level.

Storage capacity is directly related to the physical size of the read/write head. The 5.25 Apple drive can position to 70 tracks but the head is too large, so you only get 35. One method of copy protection is to use half-tracks but the tracks can not lie next to each other. You can write to track 1, 2, 3… but you can not write to track 1, 1.5, 2, 2.5… because of the size of the head. The tracks will interfere with each other.

-Why won't the HD disks work with Apple II?

High density disks have magnetic coatings of a higher "coercivity". Basically it means you need a stronger magnetic field to flip bits. The Apple drives don't provide a strong enough field, so the disks either are unreliable or, in most cases, simply don't work.

Both the controller cards shown can handle the full range of OS's mentioned here. When it comes to 5.25" FD problems, make sure all the cable plugs are well seated, then I typically go after the two big drive maintenance issues firstly;dirty heads and out of spec RPM's on the drive motor. I've posted the procedures for correcting both of those issues here on the 'Fritter, so do a search.

Sometimes the disks go south on you due to warping, or they otherwise don't freely spin in their housing. To test this hold a corner of the disk housing, insert two fingers in the hole and widen them until the contact the inner ring, then try to spin the disk to see how it moves. If it's very difficult, it might be time to destroy that disk and move on. You might still be able to copy what's on it if you're patient and keen to do so.

I've never had any more of a problem with HD disks than SD on an Apple ][, in any of the 5.25" drives.

Blimco,

http://floppydisk.com/5point25.htm

You can get Double Sided/Double Density (DS/DD)5.25 Disks here.

They should work, shouldn't they everyone?

They work for me.

I personally do not like the products sold by this site.

If you are going to buy any disk, make sure it has a ring hub. The ring hubs help to protect the disk. More importantly, they help align the disk when the door is closed. This is debatable by some but I have destroyed too many disks without hubs.

Go to the Bay if you need floppy disks and wait for a good price.