As my only working XF551 has started to behave erratically with double-density, double-sided disks, I was investigating other ways of reading Atari disks into ATR files. Does anyone have experience with the methods of the following? :

1) I found this FAQ: http://www.atarimania.com/faq-atari-400 ... pc_85.html
Oddly, all of the methods on this page only deal with single-sided floppies. Is there something strange going on with double-sided atari disks?

2) Ran across a software tool that does a bit-level image of floppies: http://www.shlock.co.uk/Utils/OmniFlop/OmniFlop.htm
It specifically reports Atari 8-bit 90K (SS/SD) format is supported. I assume from the descriptions that 180K, SS/DD should be supported
I think I'd also need to have (and/or write myself) some kind of utility to turn the image dump into an ATR file.

3) This is a hardware disk image reader that conveniently has a USB version, kryoflux: http://www.kryoflux.com/
It reports to read:
FM XFD, Atari 8-bit
MFM XFD, Atari 8-bit
I guess this means single density and double density respectively. From what I've read on their support board the multiple densities and one or two sided disks are supported.
It may also require writing a utility to turn the image into an ATR file.

4) Me, myself, and linux. A lot of assumptions here: IF the usual Atari disk formats (singe density 90K, double density 180K) are "standard" products of the drive controller and this is common to PC formats of the day, then any old PC 5 1/4 disk drive should be able to read the sectors on the disk. Therefore, I should be able to do a "dd" in linux to create a dump of a disk, and then write a simple utility to turn the image dump into an ATR file. Sounds plausible?

I just need to come up with a 5 1/4 floppy drive for a PC.

The controller with "FM" support may be able to read single density Atari disks.

A modern PC floppy controller, in all likelyhood, would only be able to read MFM encoded disks, which restricts you to enhanced or double density floppies. If you get the right controller working, then its all just a matter of getting the software to recognize the WDC 1771 track pattern and spit out an ATR disk image of the track data.

Steve

A progress report... And some questions...

I've successfully used the kryoflux and standard PC 260K and 1.2M floppy drives to read my Atari DSDD disks. Oddly, the kryoflux dtc program's built-in support for Atari DD (MFM) format would not work properly. It just generated an image of errors. Using the generic MFM format successfully imaged Atari DSDD disks.

The result of imaging a DSDD disk is two files: one for head 0, the other for head 1. The files are each exactly 720 sectors * 256 bytes long.

Oddly, the kryoflux image bytes are all bitwise complements of the real data ($00 ends up being $FF). So, it seems the data on the floppy is inverted... wonder why they decided to do that?

I wrote a little utility that flipped the byte values and now the image files match the ATR file... almost.

I should be able to generate an ATR header, and concatenate the two image files together to create an ATR file, but when I tried the file was 384 bytes too large. The DSDD image I'm working on has bootable MyDOS on it and I compared it to a known DSDD ATR image file (also with same version of MyDos) created using the ProSystem.

What I see in the ATR file is that the first 3 sectors are 128 bytes. The kryoflux image has full 256 bytes for all sectors read from the disk. The first 128 bytes of the first sector are duplicated to the second half of the first sector. Would anyone know if this is something the XF551 drive does, or is this done by software when DOS is written just to maintain OS boot compatibility?

If a disk is formatted DD, and DOS is NOT written, is the first sector still limited to 128 bytes?

How many sectors are supposed to be 128 bytes? According to the ATR file I have it looks like 3 sectors, but I read elsewhere a simple bootloader (on some game disks) may need only only 1 sector. (Yes, I read the FAQ which says 3, but I'm just checking.)

I have always been told that an Atari disk has the 1st three sectors at 128 bytes. This was a problem for me when trying to write back CP/M formatted disks on my Indus GT. Someone wrote a program to restore the missing 3 half sectors.

Ken, since XF551 drives were known to have weak SIO connecter solder connections to the main board, have you checked that out.
Intermittent contact would cause problems you may be having.
I also had problems with a 1050 drive I pulled from storage that turned out to be corrosion on the disk spindle that allowed erratic drive speed.
It was a matter of cleaning that spindle of the built up corrosion that cured the problem.
My only INDUS GT drive has a bad drive motor and I figure to swap in one from a 1050 to see if I can get it past the Controller error displayed on the front panel when I power it up.
I bought the drive out of a bin of stuff at a Goodwill as-is store and am hoping to get it to work again. It also was missing a drive belt that has since been replaced.
The 1050 drive motor is connector compatible with that of the INDUS GT.

Were the half sectors restored using an Atari drive?

Yes, and a number of other things. It's not that the "working" XF551 is having problems talking to the computer. In one particular situation the second read head isn't working. Between the two XF551 drives I have 0.75 working drives .

One drive is pretty well trashed. The power board is shot. When I swapped power boards with the "working" drive I found it would actually spin the disk, but it could only seek out to the starting track and then can't step it in. The drive makes atypical noises trying to step in. No sector data appears to go back over the SIO (to computer/sio2usb/kryoflux). This drive has had only a few months of use over its lifetime.

The "working" XF551 does work for 3 out of 4 formats: It will read single sided in either single or double density. It will read the second head, (double sided) but only in single density. In DS DD it will only read the first head, and error out on the second head. Maybe I had about six months to a year of time with this drive.

The only problem I have is Double Sided Double Density. Most of my personal working disks -- programming, etc. -- were done on the XF551s in DSDD. The rest of the disks are mostly commercial disks in single density and I have no issues there. The XF551 works still works for single sided. I also have one of those 810-on-a-plate drives that still works like a champ. I have two 1050s with double density upgrades. With sio2usb and ProSystem I should have few problems with those disks. Even if no drives worked all the old commercial software disks are already in ATR files somewhere on the internet.

In the end it looks like I can use kryoflux and a plain PC floppy drive to get back my DSDD work as soon as I finish working out how to build ATR files.

This is just a thought, but if you have access to a live linux CD, like Puppy Linux where you do not have to sudo every command, has anyone tried to use the dd command in a terminal to make an appropriately named image of the floppy?
Also, a word of caution is be sure you know how to use the dd command as one can trash a drive quickly if not used correctly.
It just seems that since it is a sort of bit-bang copy procedure, you would get an exact image in the form of a file from the disk in the drive.

The command syntax would be something like "dd if=/dev/fd0 of /mnt/home/mydisk.atr"

I have created images of floppies and also made floppies using image files.

Answering my own stupid questions here:

After reading MyDOS source code it appears 128 bytes in sectors 1 to 3 is an expectation and behavior of the floppy drive. The code goes out of its way to insure only 128 bytes can be read and written to the first 3 sectors.

I have a half dozen linux boxes. My own, so I can su freely. None have floppy disks. I'm pretty sure most don't even have the floppy disk connector on the motherboard. I'll hunt around for something ancient for experimentation. (Just remembered I have a VIA nano ITX board with floppy disk port on it. I'll have to find a case to build another box.)

If there's a problem with a sector what do you get out of dd that helps identify where the image will need to be fixed?

I also do not have a PC running linux that has a 5.25 drive and the only 5.25 drive I have in another PC is a 1.2 meg 5.25 drive.
As to your question about the first sectors on the image, they should not have to be modified.
But you could use a utility called "hexedit" to modify the ATR file if needed.
I assume that if you got an ATR of a Double Sided Double Density drive someone else had uploaded, you could examine it with hexedit to see if there are any differences. And we are talking about a true ATR image and NOT a programming ATR image here.

Yes. I followed the guide here

I created an ATR (This is not a cartridge programming image) of a double sided double density disk that was made with my XF551 drive.
I made a new ATR image of the correct type and then formatted it with Xinit in SpartaDos 3.2g and copied over all the files from the physical disk to it.
So here is the ATR image. Boot it with BASIC, and XL/XE as machine type.
You can also examine the file with a hex editor to see just how it is set up as to sector layout.
Rename the file without the zip extension to use it.
It is NOT zipped.