The Floppy Mystery
Data transfer between Atari ST and
I will try here to give first
really correct and complete explanation about troubles in data transfer
between 16-bit Ataris and PC. And of course how to do it, without data
loss, corruption. There are guides, explanations around, with incorrect
and shallow statements, which just increase already big
confusion in all this. It is last time, in few years floppies will be
out of use, new PCs will have no drives for.
Why Windows/DOS can not work reliable with
- Simplest, and safe way is
this (well known): format floppy on PC and use it for data transfer. In
Win XP type this in command prompt: format a: /t:80 /n:9 .
It will produce 720KB floppy, usable on all Ataris. If have High
density floppy drive in Atari, may use 1440KB standard PC floppies.
It will not help in transferring existing floppies, so go to point 2:
- For correct reading and
writing on PC floppies formatted on Atari (from desktop, with
diverse format programs) - collections, archives you need floppy
This is only secure way. It's not true that TOS 1.4 and above can
format PC compatible floppy. It will be explained later in deep.
- Use some good formatting
program on Atari, which can produce real PC compatible
floppies. Examples: my new Floppy Formatter
for Atari or Kobold 2.
- Extract files directly from floppies
or images. I know only one program which can extract reliable from diverse ST
format floppies in Win XP : Floppy Image
Gemulator Explorer is outdated and probably discontinued.
Because of very badly made floppy support,
drivers. Hardware is not real limit. Non-protected floppies can read/write without
errors, only problem is hyperformat, but it was unreliable on Atari too. Part of
guiltiness goes to Atari - they messed up 720K floppy format, and used
incorrect FAT length.
Atari ST's (TOS) floppy driver is very flexible, and works with
lot of different formats, while DOS/Win on PC with only few predefined.
deeper in problem:
So looks info about floppy formatted with TOS 1.4 , in Win XP:
At bottom you may see that we have 711 allocation units,
instead of 713 by standard PC 720K floppy. Yes, it is where Atari made
mistake. They set FAT length to 5 sectors instead 3, what is stupid
waste of space. But real problem is unreliable work of Windows, DOS
with such floppies. Depending on version of OS, you may expect
incorrect read of datas, FAT corruption by write and similar.
Just try to write some file on such
floppy under Win XP: - it is very slow (normally we get about
15 KB/sec). It indicates that something is wrong
Windows simple can not work well with
floppy what is not strictly DOS standard formatted. Worst in all is
despite of it, it opens and works with non-standard (for him) floppies. Check of
disk format is very superficial - if there is 0xE9 or 0xEB at start and
more-less standard BPB, such floppy will be opened.... and messed up.
Strictly PC standard 720KB floppy is: 9 sec/tr, 2 sides, 80 cylinders,
FAT size: 3 sectors (2 FAT copies), Root DIR size: 7 sectors. Total 713
allocation units (clusters) on disk.
Hurra! My PC works with 800K floppies! :
Here starts real mess. Short
said: don't trust to Microsoft! Don't read anything from such floppies
in Windows explorer, Total Commander. You will get corrupted
files with missing parts.
It sounds pretty unbelievable, and I
spent lot of time examining it: Windows will simple skip every tenth
sector of such floppies, and instead it will read following one. It
in reading different areas of disk than needed. But, for instance first
short file of 3KB will be read without error - nice to encourage
Notes: above floppy has 0xE9 at start. If formatted with another format
program (Superaccessory for instance) it will not be opened on PC.
According to my memory, Windows 95 could read such floppies correct, at
least I was able to do it in Gemulator. But it is now history.
Opening 800K floppy in Gemulator Explorer promises, Root DIR is
Not for long, opening SubDir will show garbage instead content :
After it, we may be happy that image creation of such floppy not works
at all - better nothing than corrupted image. It was under Win XP, in Win 98
it opened correct directories, but very slowly. (Imaging of floppies failed
in both OS).
Gemulator is one of rare Atari emulators which can work with floppies,
not only floppy images. But it will fail with 800KB floppies. Reason is
miserable Windows floppy driver, which skips every tenth sector on such
floppies in XP, W2K. (it stays for Gem. Explorer too, of course). On the
other side, Gemulator will work well with standard
Atari 720K floppies (those with 5 sec/FAT) - because file access goes true Atari's TOS and not
Windows, and physical format is same.
Utilities for 'making floppies DOS compatible' as ST2DOS.EXE are almost
worthless - they can not correct FAT len, or transfer 800K floppy to
720K one (what an idea! ;-) ).
Here I must to add that me, and most of Atari users in my area used very much
800K format in golden era of Atari (1987-1991). It showed as reliable, there was
couple program for creating such floppies, and Atari worked flawless with them.
It means, that there is probably still lot of such floppies.
Conclusion: use one of above mentioned 4 methods
for data transfer (and preservation) of Atari floppies, files, or
for writing files to floppies to use them on Atari.
For playing games downloaded from Internet in floppy image formats (ST,
MSA, STT) on real Atari use FloImg
- designed for Win XP (with special floppy driver), simple to use.
Use same program for transfer/image/preserve your existing diverse
format Atari, non-protected floppies, files from. It is last time for saving,
they gradually loose informations on them.
Note: there are some other Windows programs for imaging Atari ST
floppies, but they usually use Win floppy driver, and therefore will
fail with 800K floppies - for instance Wdfcopy.
Some sites with incorrect informations (list will grove):
FAQ there says that plain 720KB floppies are compatible. What is plain
720K disk is not detailed.
- it says that can work with 800K floppies, but it stays only for Win
95. Not aware about problems with FAT size.
Here is image of floppy from which I took screenshots with Gem. Explorer:
800KB image. It will work well in emulators,
but if you write it to floppy, and then try with Gemulator...
Here to mention that STE Emulator (German shareware) will even not open it, and in manual
is said why.
Quoting: "...Luckily, provided that the floppy is formatted properly, the PC can read and write to a DD disk. You will have to format the disk on your ST, as Windows XP no longer provides options to format DD disks."
- Well, they obviously don't know about command prompt. What is properly formatted DD disk remains unclear on SOS.
Steem, beginners guide says: "most disks on the ST were nonstandardly formatted in order to squeeze more onto them. Unfortunately most PC disk controllers can't read these extended formats." - Again incorrect blaming of hardware.
Nobody remember good old 800.COM for DOS?
Was it good idea, to 'blame' such sites? Maybe not. I spent lot of time
in testing, experimenting
, while I have impression that other did not so. If they can prove that
I'm wrong in something,
I will correct things here. But, unfortunatelly, based on my
experiences, most of sites will remain as it is, with all mistakes and
outdated/limited SW :-(
Some people said: why suddenly now, 21 years after launch of ST?
Because I had still some not imaged floppies, because there was need for
imaging program under Windows, which works reliable. Because I want to
see all my floppies and files on CD. Because some software simply became outdated -
incompatible with new Windows versions (it is nothing unusual).
While finished Floppy Formatter for Atari I performed lot of tests about PC
compability. Results were frustrating, unexpected.
Another frustrating factor is communication with authors of
software, actually, there is no communication at all in many cases.
10 sector/track issue is general Windows problem,
and not only by Atari ST floppies. Some people (Simon Owen
for instance) discovered it years ago, but Atari community
is after things as usual :( .
It's not easy for PC beginner to even start DOS today.
And in this case, seemingly trivial operation as floppy imaging/reading
appeared as pretty insecure and frustrating.
Pera Putnik, August 2006
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