XF551 Floppy Issues

[+Larry]

3 hours ago, Peri Noid said:

With Hyper-XF 3.5" ROM (ver.B) you can use both 3.5" and 5.25" HD mechs and format the disks to 720KB. The problem is, such a drive is no longer compatible with other Atari disk formats. I have two 3.5" drives like this and I also played with a 5.25" one.

Can you provide a little more detail about "no longer compatible?"   I have a Hyper-XF, 3.5" and format to 720K. AFAIK, acts like any other 720K Atari disk.  I don't do the partitioning, etc. I use MyDos 4.5x.

 

P.S. Haven't used it in awhile.  (It is an XF552 custom board with Hyper-XF rom.)

[_The Doctor__]

maybe the worry is the way the xf handles dsdd may be different?

[+Larry]

On 9/13/2021 at 10:52 AM, _The Doctor__ said:

maybe the worry is the way the xf handles dsdd may be different?

Yes, that has come up before for instance with the Karin Maxi drive.  It reads Track #n, Side A, Side B... rather than Side A (1-80); Side B (80-1).  But I don't recall the Hyper-XF doing that.

[Peri Noid]

On 9/13/2021 at 3:55 PM, Larry said:

Can you provide a little more detail about "no longer compatible?"   I have a Hyper-XF, 3.5" and format to 720K. AFAIK, acts like any other 720K Atari disk.  I don't do the partitioning, etc. I use MyDos 4.5x.

 

P.S. Haven't used it in awhile.  (It is an XF552 custom board with Hyper-XF rom.)

I was writing about 5.25" mechs.

 

Such a drive no longer reads SD, MD nor DD disks. Actually, it cannot read any 40-track disk, neither single nor double sided. It's becouse it actually uses only its first 40 tracks. The firmware cannot detect 40-track disk and set stepping to 2 (then it could read them but since stepping is always 1 - it cannot).

 

And if we talk about 720KB format - XF551 has a pretty unique way of track addressing - it first uses only head 0 (so the bottom side of the disk) tracks 1 to 80 and when it reaches track 80, it switches to head 1 (the upper part of the disk) but in reversed order (tracks 80 downto 1). I know only two other drives which are capable of 720KB on a 5.25" drive - Karin drive and Toms 720. Karin uses the same way of track addressing as PCs - so track 1 head 0 - track 1 head 1 - track 2 head 0 - track 2 head 1... And so does Toms, although it can recognize more disk formats (for instance standatd 360KB XF551 and any other standard Atari format). None of them can read 720KB disk formatted with XF551.

 

The same applies to a 3.5" version of XF551 but since it's actually pretty unique, nobody cares (only Karin Drive can be implemented to use 3.5" disks and then it's not XF551 compatible but it's a homebrew drive and it makes no difference anyway).

Edited September 14, 2021 by Peri Noid

[TGB1718]

On 9/14/2021 at 4:18 PM, Peri Noid said:

Such a drive no longer reads SD, MD nor DD disks. Actually, it cannot read any 40-track disk, neither single nor double sided. It's becouse it actually uses only its first 40 tracks. The firmware cannot detect 40-track disk and set stepping to 2 (then it could read them but since stepping is always 1 - it cannot).

I had a 5 1/4 drive on my ST and wanted to use it to backup my 8 bit disks which were mostly 40 track DD,

what I did to get round the 40 track issue was to build a little circuit board and a switch so it would double

step for 40 track disks, worked a treat

[Peri Noid]

Now I know one could do it - I recently bought a drive for a completly different system with a switch 40-80 tracks.

 

There's one more thing about 80 track drives, when applied to 40 track disks - 40 track drives have wider heads and "draw" wider tracks (what I've been told). So although it is pretty safe to read such a floppy in an 80 track drive, modifficaitions can be problematic if a 40 track drive is then used.