Disk signature on "pre-formatted" disks

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Darkstar
Posts: 72
Joined: Thu Nov 04, 2010 7:58 pm

Disk signature on "pre-formatted" disks

Post by Darkstar »

Hi,
I was dumping a few old disks with my stuff on it today, and I discovered that strangely, one of the dumps had a different size than all the others (1.492.992 bytes instead of 1.474.560) which is exactly 1 track, 2 sides, 18sectors/track more than a "regular" dump.

The additional track was filled with @-characters and this "signature":

Code: Select all

@@@@11/27/94 05:23@@0404 B88   @@@@@004519@@@@@@@@@@sma4-25n4-01@@@
I'm pretty sure I didn't have any equipment back then to format the disk with more than 80 tracks (I think standard FDCs were not able to do that). The disk in question is a Sony "DOS formatted" disk that probably came preformatted when I bought it, so I guess this must be some sort of signature that the manufacturer put on the disk. Was that common practice back then? Or maybe it is something entirely different? googling for the signature turned up nothing helpful...


-Darkstar

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karadoc
Posts: 139
Joined: Sun Oct 31, 2010 9:12 pm

Re: Disk signature on "pre-formatted" disks

Post by karadoc »

Yes, we certainly see a lot of that sort of thing with the games we have preserved within SPS. I wouldn't be able to give you any statistics, but it is definitely common, yes.

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IFW
Posts: 3079
Joined: Mon Nov 08, 2010 2:42 pm

Re: Disk signature on "pre-formatted" disks

Post by IFW »

Yes, it was often used to track duplication; it's the first unused track on a disk, e.g. 80.0 on double sided 80 tracks disk.
You can force DTC to stop processing those tracks by setting the endtrack in the example case as -e79

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IFW
Posts: 3079
Joined: Mon Nov 08, 2010 2:42 pm

Re: Disk signature on "pre-formatted" disks

Post by IFW »

By default DTC autodetects disk usage for sector dumps as that is the preferred behavour.

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