8" CDC/MPI drive says max track is 41 ??

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SteveConley
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Joined: Tue Oct 23, 2018 2:52 pm

8" CDC/MPI drive says max track is 41 ??

Post by SteveConley » Fri Oct 26, 2018 3:40 am

(Background ... I used to design CP/M and MP/M computers and program 1791 controllers etc back in the early 1980s. But that was a long time ago ...)

So I made a 8" to 5-1/4" converter cable for the KryoFlux which I checked out on a 3-1/2 floppy and learned the GUI tool.

My problem is that with an 8" SSSD disk - from factory never written ...

First the calibrate says I only have tracks 0-41.
Well ... I should have 77 as I remember ...
Second, it reads those 42 FM tracks it finds nicely with track 0 being the index with 26 sectors with "stuff" in the first 80 bytes and 0's of the 128.
Tracks 1 to 41 are filled with E5's (26 x 128)

I have read in the diskette as preservation mode and analyzed it and it shows no transistions on side 1 as appropriate.

But what happened to my other 77 - 42 tracks ??

Is there something obvious I am missing ? I have scanned the 28 pages of forum stuff and haven't seen anything.

The Drive is a Control Data Corporation, Magnetic Peripheral Inc, model BR8A8-A or pn 77618026.

The drive "worked" when I put it away about 25 years ago - in a HEAVY enclosure, and sealed from additional dust.

Power supply voltages (24, 5) look fine.

All looks good except # of tracks.

Thanks,
Steve

SomeGuy
Posts: 179
Joined: Wed Feb 18, 2015 8:18 pm

Re: 8" CDC/MPI drive says max track is 41 ??

Post by SomeGuy » Fri Oct 26, 2018 4:01 am

It sounds like the KF may just be getting the max track value wrong. It may be the kryoflux only tests for 40 and 80 track drives.

I'd just manually feed in "77" tracks as the maximum value. Then when reading a disk listen closely for any abnormal sounding behavior, and stop it if there is.

In what you dumped, were any track number ID mismatches reported?

Are you just reading disks, or do you plan to write?

SteveConley
Posts: 7
Joined: Tue Oct 23, 2018 2:52 pm

Re: 8" CDC/MPI drive says max track is 41 ??

Post by SteveConley » Fri Oct 26, 2018 12:37 pm

Ok, I actually have 4 of these drives - identical except for serial #.

I could not even see the manufacturer because of the way they were mounted (2 with huge power supply and fan).

So I took one out last night to get the manufacture and #.

Today I disassembled the whole thing, and tried a different drive from the other cabinet. Besides the fact that whoever put that one together had reversed one of the data cable connectors (!) but had plugged the connnectors (not keyed) into the driver the other way ...

The second drive does EXACTLY the same thing.
Even "dtc -c2" returns max track 41. But it "seems" watching the drive now, that it is seeking the whole way, and the UI seems to flash (quickly) 1, 39, 40, 41, 49 (?) and 79.

So it is TRYING all the way to 79 - could that be the reason ??

But you would think that it would see that "49" was ok, and list that ??

Anyway, to the other question you asked, yes the track matches on the reads perfectly from 0-41.

I am now double perplexed - because I thought maybe there was something stopped the drive from seeking all the way on that one, but no - it appears to seek all the way and the other drives does identically.

I am about to wear out my USB from from plugging it in and out ...

Steve

SteveConley
Posts: 7
Joined: Tue Oct 23, 2018 2:52 pm

Re: 8" CDC/MPI drive says max track is 41 ??

Post by SteveConley » Fri Oct 26, 2018 1:00 pm

BTW, to be more specific - at this point I am only trying to get the "max track" working ... and I see no way to tell DTC how to not go beyond 76. I tried the command:

dtc -e76 -c2

and it still returns max track 41.

as does -e45. Which from looking at it - seems to try seeking all the way to 79 anyway.

It also does not seem to generate a log when doing the calibrate test. (or at least I cannot find it).

For full disclosure, I am running this on 64bit Win7 Pro.

Thanks,

Steve Conley

SteveConley
Posts: 7
Joined: Tue Oct 23, 2018 2:52 pm

Re: 8" CDC/MPI drive says max track is 41 ??

Post by SteveConley » Fri Oct 26, 2018 5:39 pm

I am giving up until I can find more data.

I have been able to find a manual that "is close" to the drive:
77614903AM_9406_Flexible_Disk_Description_Jun82

but mine is a 77618"026" and that manual covers overs 019 and skips to 028.

but it "seems" to be the same unit and all it says makes sense on the hookup.

ALSO, the directions I initially saw on the internet for making the conversion cable was unclear as to whether to attach drive 8, 12, or 22 to the controller line 34.
It was written by Herb Johnson, and he said he excerpted it from the 12/20/2006 CP/M FAQ.

I initially connected it to 12 as the directions "seemed" to be saying, but I just changed that to 22 - which actually seemed better given the documentation. But ... no change. Seemed to make no difference at all.

8" drive:
8 = True Ready (except it does not appear this drive provides that)
12 = Disk Change (This is actually enabled by a jumper on the driver - and factory has it not enabled.
22 = Ready (the description for this seems like it is what you want).

Controller:
34 = DiskChange / Ready (Disk Change = 1, Ready = 0)

Steve Conley

SomeGuy
Posts: 179
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Re: 8" CDC/MPI drive says max track is 41 ??

Post by SomeGuy » Fri Oct 26, 2018 6:07 pm

I'm a little confused here about what you are trying to do. If you can read the first 40 tracks then your adapter is correct, at least for reading.

I just did a little test with my 1.2mb 5.25" drive. If anything blocks the head from reaching track 80 during calibrate, then it assumes there are 41 tracks. So, the kryoflux software knows nothing about 77 track drives.

In the GUI you simply enter the actual maximum tracks in to the settings dialog.

I believe the DTC command line tool does not even remember or enforce maximum track value. You are supposed to pass the number of tracks to read on the command line.

I've got an 8" floppy drive too that I have previously used with my Kryoflux, but as I recall (it was a while back) mine can step to track 79 (80 tracks) so I may not have run in to that specific problem.

Now, there are a couple of issues to watch out for when writing, but that is another ball of wax.

SteveConley
Posts: 7
Joined: Tue Oct 23, 2018 2:52 pm

Re: 8" CDC/MPI drive says max track is 41 ??

Post by SteveConley » Fri Oct 26, 2018 10:21 pm

I HAVE used the -e76 and lessor values as I described above.

But no matter it refuses to go past 41.

I have set the profile to last track 76 ... still no dice - although the calibrate function appears to not look at the profile - because there is not one "specified" for a calibrate.

And I do see it seek - looking at the UI during calibrate, eventually (after the 0, 39,40,41) to 49 and then to 79.

I think the firmware has a bug "now" which assumes if you do not have 79 and you have 41, then you must be 41 max track. And then the read functions refuse to go past that value.

I am assuming the algorithm for "calibrate" (since it functions even without a disk inserted), finds track 0, then steps X times to get to track X, and then steps BACK X times continually looking for Trk0 signal.
If it sees track zero BEFORE X steps back, it assumes there was no track X.

Since it does not "try" anything but the 40's and 79, then it makes the assumption there is no higher track.

The choice of the 49 I see on the display seems strange to me, almost like that is the error.
Unless the idea was to see if there was something past 41, and to "remember" that, and then if 79 did not exist, it should start backing off of 79. But of course it is not doing that.
So it seems like a bug to me.

ZrX
Posts: 484
Joined: Tue Dec 06, 2011 9:09 pm

Re: 8" CDC/MPI drive says max track is 41 ??

Post by ZrX » Fri Nov 09, 2018 8:17 pm

We have dumped several 8" disks with 77 tracks without any issues, tho that was done via command line only. Can't actually say if the GUI really has some problems doing this as I never use it.

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mr.vince
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Re: 8" CDC/MPI drive says max track is 41 ??

Post by mr.vince » Sun Nov 11, 2018 11:17 am

You can always manually set max track in the GUI regardless of auto detection.

rcade
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Joined: Mon Nov 21, 2011 5:21 pm

Re: 8" CDC/MPI drive says max track is 41 ??

Post by rcade » Thu Nov 29, 2018 5:34 am

Ignore the -c2 detection, forget about it. You can't override it, and it doesn't matter!

Just read the disk as you normally would with -e77, or are you saying it will not let you even read past 41?
-
Pete Rittwage
C64 Preservation Project
http://c64preservation.com

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