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CPM 8" DSDD .imd decode

Update,

I'm trying to confirm my SA850 drives can access the 2nd head and am having lots of trouble.
Adaptec 1522CF on a DOS PC with imagedisk and 22disk and anadisk.
No trouble reading/writing 5.25, 3.5 drives.
I'm using the S2 option jumper, everything looks right.
I SHOULD be able to FORMAT B: /F:360 and succeed but DOS 5.0 and 3.31 spit out error m20241009_162653.jpgessages when they get to the 2nd head. Not read.I've tried my own DIY 34-50 board, the DBIT and the texelec, with all the same results.I've tried as many jumper configs as I can think of.
I'm neck deep in this and need to get this resolved before I can confidently tackle the ibex ideas suggested.
 
Not really, the HD 5.25 is pretty much identical to the 8" disks. There's also a HD 3.5" 360 RPM variant seen on a lot of Japanese hardware. The idea is to keep the format constant among physical sizes.

8" drives are all high-density (500K data rate), so a 360KB format isn't possible. Try 1200KB instead.
 
Wow I'm just stumped here trying to prove my 8" SA850 can actually r/w head #2.
If there is something wrong with my setup this would prove why I'm getting a bogus ibex disk reading on imagedisk.

I thought I could just format a DSDD 8" diskette in DOS as 1.2m and have it error out at tk 78
but it tells me invalid media when it moves to the 2nd head on tk 0.

I've tried every possible jumper config, tried every converter board, tried V3.3 and V5 of MSDOS, tried various FORMAT parameters - all fail.
Tried changing drive setting in the CMOS config, all fail.

Imagedisk will do a format on DS and shows me it moving the head but that just tells me it thinks it's writing.
I've actually never proved my system can write head 2 on this setup.

stumped.
 
Try doing it on an HD (1.44M) 3.5 disk. That should work. Also, the top head on an SA800 series drive is the second head. Also, make sure you're using DS 8" media--there are two flavors--SS and DS, with differently placed index apertures.
 
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Yep, trying both SS and DS media with the index hole more off-center.
I've tried configuring it as a 1.44 but I wouldn't expect that to work due to the spindle speed of 300RPM, the software can tell by reading index.
I'm just stumped, I should be able to config an MSDOS machine for 1.2M drive, and FORMAT this 8" DS drive, and only have problem on the last 3 track, but I cant.
There is something basic I'm missing.
 
Yes, I can R/W 3.5 and 5.25 DS drives on this Adaptec controller just fine.
But can't confirm 8".
8" SS works fine, IMD, 22DISK, ANADISK.
 
I'm completely stumped.

I can not get an SA850 drive to read the 2nd head on a DOS machine.
This drive should act like an 80 track drive up till tk 77 but it fails when it switches to the 2nd head on tk 0.
It formats side 0 then fails after switching to side 1 with invalid media (general purpose error).

I've gone to the effort of building a FD breakout box to help troubleshoot.
The side-select is wired and jumpered correctly

I've tried 4 SA850 drives, they all act the same. Maybe all 4 are bad - strange.
I've tried every known jumper setting.
I've stayed up nights for weeks reading the docs from every source - OEM, service manuals, etc.

If I short the SIDE select signal to always be on side 1 then it fails immediately, telling me that my drive is failing on side 1.

Yes, I'm using double-sided media with the offset index hole, I know this stuff well. I'm getting index pulses.

These 4 drives all read single-sided disks fine on my DOS machine running Imagedisk and 22disk.
I can read SSSD CPM directories.
But I can not read the 2nd side.

I've scoped out the lines and all seems fine. Ready doesn't go away on side 1 select, nor write protect, and I see read data on side 1 at the connector.

This is why my IBEX disks are the same on both sides because I had a jumper setting that was always selecting side 0 so both sides ended up the same.

I'm at a loss what to do now.

Maybe ALL 4 of my SA850 drives are bad on side 1 but otherwise completely work - possible but strange.
 

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FOR VERSION 1.42 OF 22DISK

BEGIN SAN3 Sanco 7202 DSDD 48tpi 500kbps 8"
DENSITY MFM ,HIGH
CYLINDERS 77
SIDES 2
SECTORS 26,256
SIDE1 0 1,7,13,19,25,5,11,17,23,3,9,15,21,2,8,14,20,26,6,12,18,24,4,10,16,22
SIDE2 1 1,7,13,19,25,5,11,17,23,3,9,15,21,2,8,14,20,26,6,12,18,24,4,10,16,22
ORDER SIDES
BSH 5 BLM 31 EXM 0 DSM 240 DRM 127 AL0 080H AL1 0 OFS 4
END
 
I don't see the point of the Sanco definition post. The OP's problem is that his drives don't want to do double-sided.

The proper approach it seems to me, is to take out your 'scope and see what's happening with the second side.
 
"This is why my IBEX disks are the same on both sides because I had a jumper setting that was always selecting side 0 so both sides ended up the same."

I don't really understand what you mean here.
If you put side 0 data on side 1 the floppy controller may be checking the side bit in the header and it will never match.

Since you have four drives all acting the same I don't think it's a bad drive.
 
jlang said:
If you put side 0 data on side 1 the floppy controller may be checking the side bit in the header and it will never match.
Click to expand...
More than a few drivers ignore the side mismatch, although AnaDisk will diagnose the issue. One of the schemes used to tell different floppy formats apart was to use, say, 128 as a side ID for one format. The disk format could then be determined with a simple READ ID operation.
 
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