Why is maxtrack limited to 83?

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Malvineous
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Why is maxtrack limited to 83?

Post by Malvineous »

I've noticed that there is an option in dtc that will let you set the maximum track number, however this can't be set above 83. The -c2 calibration option also doesn't check above track 83.

I am curious as to why this is the case. Is there some limit that says you cannot have track 84? Given that there are a few drives that go all the way up to track 83, wouldn't it make sense to see if they can also reach track 84?

I just posted a link in the feature requests forum to some Linux code I wrote to perform the -c2 operation, but out of curiosity I tried telling the KryoFlux to use track numbers higher than 83. This worked (the KryoFlux accepted the setting), although I was still getting maxtrack=81 and maxtrack=83 depending on the drive I used. But then I stumbled across a Samsung drive that got all the way up to track 85 before returning errors!

I am not sure whether this is just some artefact or whether it really is reading up to track 85, but it sure is intriguing! Here is the output (from my program, not DTC) for this drive:

Code: Select all

0058931d: status=0
Resetting device...
00589331: reset=0
0058966d: status=0
Reset complete.
00589681: descriptor=C2 DiskSystem/version=1.00/date=Oct 12 2010/time=20:06:17
00589695: device=0
005896a9: density=0
005896bd: min_track=0
005896d1: max_track=87
005896e5: motor=1
005899f6: side=1
00589a0a: track=0
00589a1e: motor=1
00589a32: side=1
00589a46: track=0
00589a5a: motor=1
00589a6e: side=1
00589a82: track=78
00589b96: motor=1
00589baa: side=1
00589bbe: track=0
00589cd2: motor=1
00589ce6: side=1
00589cfa: track=0
00589d0e: motor=1
00589d22: side=1
00589d36: track=79
00589e4d: motor=1
00589e61: side=1
00589e75: track=0
00589f8c: motor=1
00589fa0: side=1
00589fb4: track=0
00589fc8: motor=1
00589fdc: side=1
00589ff0: track=80
0058a10b: motor=1
0058a11f: side=1
0058a133: track=0
0058a24e: motor=1
0058a262: side=1
0058a276: track=0
0058a28a: motor=1
0058a29e: side=1
0058a2b2: track=81
0058a3d0: motor=1
0058a3e4: side=1
0058a3f8: track=0
0058a516: motor=1
0058a52a: side=1
0058a53e: track=0
0058a552: motor=1
0058a566: side=1
0058a57a: track=82
0058a69b: motor=1
0058a6af: side=1
0058a6c3: track=0
0058a7e4: motor=1
0058a7f8: side=1
0058a80c: track=0
0058a820: motor=1
0058a834: side=1
0058a848: track=83
0058a96c: motor=1
0058a980: side=1
0058a994: track=0
0058aab8: motor=1
0058aacc: side=1
0058aae0: track=0
0058aaf4: motor=1
0058ab08: side=1
0058ab1c: track=84
0058ac43: motor=1
0058ac57: side=1
0058ac6b: track=0
0058ad92: motor=1
0058ada6: side=1
0058adba: track=0
0058adce: motor=1
0058ade2: side=1
0058adf6: track=85
0058af20: motor=1
0058af34: side=1
0058af48: track=0
0058b072: motor=1
0058b086: side=1
0058b09a: track=0
0058b0ae: motor=1
0058b0c2: side=1
0058b0d6: track=86
0058b203: motor=1
0058b217: side=1
0058b22b: track=65535
0058b352: motor=0

maxtrack=85

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IFW
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Joined: Mon Nov 08, 2010 2:42 pm

Re: Why is maxtrack limited to 83?

Post by IFW »

84 is the limit most manufacturers would use.
Duplicators wouldn't normally touch anything above 80 though for valid data - apart from some games, it's usually traceback info they'd put there.

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Malvineous
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Re: Why is maxtrack limited to 83?

Post by Malvineous »

Is it worth increasing the limit to allow dtc to both report the real number of tracks the drive can access, and to potentially dump them just in case there is ever data there? I just found the NEC 1157C (5.25") can read 85 tracks (maxtrack=84).

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IFW
Posts: 3079
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Re: Why is maxtrack limited to 83?

Post by IFW »

We can get the drive off track there, if there is no hard stop on the rail. Not sure, if it's a real world issue though...
It could be optional for playing it safe, or not.

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Malvineous
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Re: Why is maxtrack limited to 83?

Post by Malvineous »

Well I would certainly vote to add a "-breakmydrive" option to dtc to remove any safety limits :-) FWIW none of the drives I have tested have had any mechanical problems attempting to seek past track 83 - they do make an odd click on the first track past whatever their max is, but dtc doesn't push any further than that so I think the risk is pretty minimal anyway.

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