Hard sector format
Re: Hard sector format
Hi, Jeff. I will dig up all the information and send it to you.
When you say "share some images" are you talking about raw data or Kryoflux?
When you say "share some images" are you talking about raw data or Kryoflux?
Re: Hard sector format
I have the information on Northstar hard-sector diskettes and it looks complete. Unfortunately, the forum will not accept a PDF upload. Can you suggest any way for me to get this to you?
Re: Hard sector format
Now I'm even more confused. It appears I did send you the PDF on Northstar format and it has a complete description of the layout, including the CRC algorithm. What do you feel is missing? I'll try to clarify.
Re: Hard sector format
This is the 2 pages pdf ? The Crc description is not complete : missing size, polynomial, start value...
the sector header description is not detailed enough... (mismatch between the text and the diagram)
a second information source may help me to understand it.
Re: Hard sector format
The CRC description looks complete to me. Here's how I interpret it:Jeff wrote: ↑Tue Oct 03, 2017 11:01 pm This is the 2 pages pdf ? The Crc description is not complete : missing size, polynomial, start value...
the sector header description is not detailed enough... (mismatch between the text and the diagram)
a second information source may help me to understand it.
Code: Select all
unsigned char data[512];
unsigned char crc = 0;
for (int i=0; i<512; i++) {
crc = crc ^ data[i];
crc << 1;
}
Code: Select all
static unsigned char ns_csum(unsigned char *buf, int count) {
unsigned char csum=0;
while(count--) {
csum^=*buf++;
csum=(csum<<1)|(csum>>7);
}
return csum;
}
The diagram is correct as I commented in my original post. There are 33 bytes of zero and 512 data bytes. The only missing item is the track/sector id and I will look for that information.
Does this help?
Last edited by snhirsch on Wed Oct 04, 2017 12:01 am, edited 1 time in total.
Re: Hard sector format
not really a crc, that's why i am not sure at allsnhirsch wrote: ↑Tue Oct 03, 2017 11:52 pmThe CRC description looks complete to me. Here's how I interpret it:Jeff wrote: ↑Tue Oct 03, 2017 11:01 pm This is the 2 pages pdf ? The Crc description is not complete : missing size, polynomial, start value...
the sector header description is not detailed enough... (mismatch between the text and the diagram)
a second information source may help me to understand it.
Code: Select all
unsigned char data[512]; unsigned char crc = 0; for (int i=0; i<512; i++) { crc = crc ^ data[i]; crc << 1; }
Yes track/sector is missing, and i suspect that some other things are missing.
Btw is this use FM encoding ?
Re: Hard sector format
I posted some known-working code above. The shift is actually a roll around, but it is simple-minded.
The encoding for 512 byte sectors is MFM.
I'll try to get David Schmidt involved in this discussion, since he wrote the decode routines for the DeviceSide reader. His code saves out only decoded sector data so it isn't directly useful for generating an image. However, I think he deciphered all the pertinent aspects of the disk layout.
The encoding for 512 byte sectors is MFM.
I'll try to get David Schmidt involved in this discussion, since he wrote the decode routines for the DeviceSide reader. His code saves out only decoded sector data so it isn't directly useful for generating an image. However, I think he deciphered all the pertinent aspects of the disk layout.
Re: Hard sector format
Ok ! Please share some raw image (not kryoflux), i will start a loader skeleton.snhirsch wrote: ↑Wed Oct 04, 2017 12:04 am I posted some known-working code above. The shift is actually a roll around, but it is simple-minded.
The encoding for 512 byte sectors is MFM.
I'll try to get David Schmidt involved in this discussion, since he wrote the decode routines for the DeviceSide reader. His code saves out only decoded sector data so it isn't directly useful for generating an image. However, I think he deciphered all the pertinent aspects of the disk layout.
Re: Hard sector format
I instrumented the DeviceSide client program to dump track/sector bytes from a single-sided diskette and came up with this:
That's 35 tracks, 10 sectors per track. The upper four bits cycle 0, 4, 8, C, 0, etc, etc. so not really a track marker. I checked several disks to make sure - that's definitely what's there, as strange as it is. Lower four bits are sector number with +4 physical skew.
UPDATE: I was able to read a double-sided diskette. One the second side, the upper four bits cycle 1, 5, 9, D, 1, 5, ... So they use the low-bit on the upper nibble to mean "side 2". Otherwise exactly the same.
How can I get a sector image to you?
Code: Select all
00 02 04 06 08 01 03 05 07 09
40 42 44 46 48 41 43 45 47 49
80 82 84 86 88 81 83 85 87 89
c0 c2 c4 c6 c8 c1 c3 c5 c7 c9
00 02 04 06 08 01 03 05 07 09
40 42 44 46 48 41 43 45 47 49
80 82 84 86 88 81 83 85 87 89
c0 c2 c4 c6 c8 c1 c3 c5 c7 c9
00 02 04 06 08 01 03 05 07 09
40 42 44 46 48 41 43 45 47 49
80 82 84 86 88 81 83 85 87 89
c0 c2 c4 c6 c8 c1 c3 c5 c7 c9
00 02 04 06 08 01 03 05 07 09
40 42 44 46 48 41 43 45 47 49
80 82 84 86 88 81 83 85 87 89
c0 c2 c4 c6 c8 c1 c3 c5 c7 c9
00 02 04 06 08 01 03 05 07 09
40 42 44 46 48 41 43 45 47 49
80 82 84 86 88 81 83 85 87 89
c0 c2 c4 c6 c8 c1 c3 c5 c7 c9
00 02 04 06 08 01 03 05 07 09
40 42 44 46 48 41 43 45 47 49
80 82 84 86 88 81 83 85 87 89
c0 c2 c4 c6 c8 c1 c3 c5 c7 c9
00 02 04 06 08 01 03 05 07 09
40 42 44 46 48 41 43 45 47 49
80 82 84 86 88 81 83 85 87 89
c0 c2 c4 c6 c8 c1 c3 c5 c7 c9
00 02 04 06 08 01 03 05 07 09
40 42 44 46 48 41 43 45 47 49
80 82 84 86 88 81 83 85 87 89
c0 c2 c4 c6 c8 c1 c3 c5 c7 c9
00 02 04 06 08 01 03 05 07 09
40 42 44 46 48 41 43 45 47 49
80 82 84 86 88 81 83 85 87 89
UPDATE: I was able to read a double-sided diskette. One the second side, the upper four bits cycle 1, 5, 9, D, 1, 5, ... So they use the low-bit on the upper nibble to mean "side 2". Otherwise exactly the same.
How can I get a sector image to you?
Re: Hard sector format
Hi, Jeff. Do you have everything you need regarding the Northstar format? I believe I've addressed all your questions.
Would still like to send you a sector data image, but need a valid e-mail address since the forum won't permit code uploads.
Would still like to send you a sector data image, but need a valid e-mail address since the forum won't permit code uploads.
Re: Hard sector format
Send me the images to hxc2001 at hxc2001.com
Re: Hard sector format
Hi, Jeff.
Just wanted to make sure you have the images and check whether you know have all the information needed to emulate the NorthStar diskettes?
Just wanted to make sure you have the images and check whether you know have all the information needed to emulate the NorthStar diskettes?
Re: Hard sector format
yes got them.
I really miss a kf still raw dump to be sure about the physical format...
I really miss a kf still raw dump to be sure about the physical format...
Re: Hard sector format
I'm not a KF expert. If you can give me a starting point for the myriad of command line switches I'll be glad to give it a shot.
Re: Hard sector format
Jeff,
From what I've been able to determine the Kryflux cannot process hard sector diskettes. I really think this should be possible without it.
If Dave Schmidt has a Catweasel image, would that be something you can work with?
From what I've been able to determine the Kryflux cannot process hard sector diskettes. I really think this should be possible without it.
If Dave Schmidt has a Catweasel image, would that be something you can work with?