Search found 51 matches

by obo
Thu Jul 11, 2013 8:32 am
Forum: Other emulators & tools
Topic: Writing Atari ST programs onto floppies with PC
Replies: 26
Views: 30702

Re: Writing Atari ST programs onto floppies with PC

You'll (almost) always be limited to a 9-sector 720K format when dealing with double-density disks in USB floppy drives. The problem is that they're addressed using logical block numbers, like modern hard disks, and the mapping from LBA to CHS (+FDC access) is hidden within the drive unit. That mean...
by obo
Fri Mar 23, 2012 4:44 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

Re: Trouble using FloImg or FdRawCmd

Well, they're still unreliable with PC floppy controllers! The best I could do in SAMdisk was to warn if there appeared to be a sector missing from the start of the track -- it can tell that from the time between start of track and seeing the first sector header. I've tried other tricks to read them...
by obo
Mon Jul 07, 2008 1:31 pm
Forum: News & Announcements
Topic: SainT v2.10 released!
Replies: 18
Views: 4269

Re: SainT v2.10 released!

leonard wrote:theorically FdRawCmd.sys should run on vista (but i don't know for 64bits version).

The 64-bit version was developed on Vista, so it's definitely supported!

Congrats on your SainT release supporting it :)

Si
by obo
Tue May 13, 2008 10:18 pm
Forum: Other emulators & tools
Topic: Writing Atari ST programs onto floppies with PC
Replies: 26
Views: 30702

Re: Writing Atari ST programs onto floppies with PC

Writing 11-sector disks isn't too difficult on the PC, it's generally just a problem reading such disks that were formatted on the ST. The first sector position and minimal gaps are usually too tight for the PC controller to handle, and even if it can see the sector headers the data may be too clos...
by obo
Sun Dec 31, 2006 6:36 pm
Forum: Floppy Disk Preservation
Topic: Copy Protection Information: Weak Bits, Bit-rate ...
Replies: 97
Views: 57575

But, nevertheless I will continue to collect information, perform test on the subject and update my document accordingly (at least for me). Obviously it would have been easier to get help but I know that not all people like to share their knowledge. I've very much enjoyed reading your document, whi...
by obo
Sun Dec 31, 2006 3:35 pm
Forum: Floppy Disk Preservation
Topic: Copy Protection Information: Weak Bits, Bit-rate ...
Replies: 97
Views: 57575

You changed your wording (as the bolding shows). So it seems you realized how that sector could be created, don't you? :) Why the riddles? Why not just explain in full without leading him to the solution or getting him to read back to previous messages? It's very patronising. DrCoolZic: The sector ...
by obo
Thu Sep 28, 2006 7:21 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

So "fast format" doesn't mean, as we all though, that it will read faster. Just that it will format faster. ... and leave behind whatever was on the end of track before!? Still, it's fairly unlikely to be a sector header if the disk was previously formatted as 512-bytes/sector as it shoul...
by obo
Tue Sep 26, 2006 9:15 am
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

I start to believe that this thread is caused by bug in FC pro. There's nothing wrong with FC Pro - it does exactly what it's supposed to do, and you've used it yourself for years without complaint! It's just unfortunate that it strays from the IBM standard format enough to cause us problems readin...
by obo
Mon Sep 25, 2006 12:07 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

I will make test floppy on Atari with short intersector GAPS to test it. But it will not help in reading... OK, we will know it too :D Don't forget to write something to the disk after/during formatting, to break up the single formatting stream. Freshly formatted disks will be much easier to scan t...
by obo
Sun Sep 24, 2006 10:55 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

Drive select tricks might help. But again, other ways of reading might help as well. Anything seems worth a go! I'm particularly interested in a solution using standard hardware only, as it makes it easy for anyone to set up. Even the requirement of having 2 floppy drives is a problem, as more moth...
by obo
Sun Sep 24, 2006 10:38 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

2) your "read id" step. What does it mean exactly? The controller goives you a list of position of secteor data, sector header? If "read sector" or "read track" fail, what's the advantage of that method? The read-id command just returns the header details for the next ...
by obo
Sun Sep 24, 2006 8:05 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

Has anyone ever written a program to try reading foreign format disks using an external USB 3.5 Floppy drive ? Surely these have a customised controller interface built in which would avoid some of these issues. The drive units do contain their own floppy controller chip, but it's not accessible th...
by obo
Sun Sep 24, 2006 7:45 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

But it is wrong to say that MFM encoded at DD is 500Kbps as Wiki claims. In first place because once data is encoded, the concept of bits doesn't exist anymore. Maybe we're just thinking in terms of the different sides of the controller? :) I usually think of what is visible from the host side, whi...
by obo
Sun Sep 24, 2006 4:34 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

I wonder if I could write a "universal" disk reader on PC. That's exactly what Vincent had in mind for Disk2FDI, and why his image file format is very flexible. I believe he already has decoders for FM, MFM and GCR, as well as the slightly different format needed for the Amiga, and maybe ...
by obo
Sun Sep 24, 2006 4:30 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

MFM does NOT use one clock transition per data bit. That's the whole point of MFM vs. FM. And therefore the flux transition rate on the disk surface is still 250Ktps, not 500Ktps. The effective bitrate is still 500Kbps on a 250Kbps track, when you consider both the data and clock bits that can be r...
by obo
Sun Sep 24, 2006 4:20 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

Btw, How can I know which read-sector fail? When I execute "read data" for 10 sectors, if it returns true then I know it's ok, and if it returns false maybe some sectors are ok. How can I know what sectors are ok ? Use IOCTL_FD_GET_RESULT to read the controller result bytes after failure....
by obo
Sun Sep 24, 2006 4:17 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

I enderstand with your explain that maybe the fact the index mark detector is not active could explain that. so suppose index mark is not active, why can't I find "A1A1A1" pattern for some headers? You're relying on the controller returning the data stream, which is only half the track bi...
by obo
Sun Sep 24, 2006 2:28 am
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

But, is it possible that "0xa1" for exemple is stored in more than 8bits? (I mean, 9 bits?). so depdening of the drive speed some inner bits can be dupplicated? The bitstream will be consistent in all places except the write-splice points, so the 0xa1 will always be 8 clean data bits (plu...
by obo
Fri Sep 22, 2006 11:26 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

60 extra bytes sounds a bit too much for the extra header. I don't know how accurate are your measurements, but the difference should be less than 40 bytes. The scanning measurements are usually accurate to within a couple of bytes, with interrupt processing being an unavoidable factor. As a sample...
by obo
Fri Sep 22, 2006 5:01 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

I get the same result as my program (even without the bitstream shift, I saw sometimes I lost sync just by looking at an hexa viewer :-)) I started with the hex editor too, which was enough to show it was probably worth decoding properly. I say "properly", but my parser is very crude, and...
by obo
Fri Sep 22, 2006 3:31 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

I made some fast test with read-track command, reading 8192 raw bytes. I wrote a quick version at lunchtime too, which you can download from: http://obo.homeip.net/DiskTest01.zip I've included source code so you can tweak it if you feel the urge - it was a bit of a rush job so I'm not promising it'...
by obo
Fri Sep 22, 2006 3:14 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

Although, sometimes the READ ID command can be succesful after 55 or more tries on some of the "first sectors" (and consequently, the READ command is succesful too). It can be a matter of hours to image a single disk! I can imagine that small variations in rotation speed could bring some ...
by obo
Fri Sep 22, 2006 3:07 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

thanks obo for details. Sorry for my lack of knowledge of PC driver, but is this possible (or not): No worries - the general PC controller operation isn't too different from the WD1772, but there are a number of extra quirks and restrictions. Start a "read sector" (not a read track) on se...
by obo
Thu Sep 21, 2006 10:29 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

I made some fast test with read-track command, reading 8192 raw bytes. I noticed the bit stream is not valid very fastly (about 1000 bytes). the clock is lost and some dummy bits seems to appairs , shifting all the rest. The first 512 bytes of the data will be the data field for the first visible s...
by obo
Thu Sep 21, 2006 10:14 pm
Forum: Other emulators & tools
Topic: Trouble using FloImg or FdRawCmd
Replies: 135
Views: 49780

Those are precisely the extra dummy headers, they must be "strange". The whole point is to insert a header alone, without the actual sector. Because the idea is that the next sector would be very close after the seek with verify. And then it must have an unused/strange sector number. The ...

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