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Keatah

Wiping the VTOC

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Like most hard disks and other floppy systems, deleting something on a standard 143K Apple diskette doesn't really delete anything. It just writes to VTOC and that's it. Both the program and it's VTOC entry are available for recovery at a later date. So what programs are available that will clear both VTOC and the data area of the deleted program?

 

(Initializing a disk does the job in a brute-force blanket way. Giving you a fresh disk from which to start.)

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I'm using the "Certify & erase disk" from EDD. It erase the entire disk using half tracks. It may requires the EDD card though.

I think you could also use the "Disk Drive Test/General Operation" from MECC Computer Inspector as it erase the entire disk.

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Totally forgot to mention I wanted to keep valid data on the disk, intact. Just erase the un-used VTOC entries and the sectors they point to.

 

Not so much for security. But for other reasons like zipping a disk to its smallest size possible.

 

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Since you rarely zip a disk until all the files on it that you want, just do a file copy to a fresh inited disk.  This also has the added affect of de-fragmenting a disk so files load faster.

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Mmm yes probably so. I wanted to see how far they took disk optimization back in the day.

 

With Zmodem protocol, whenever there was a string of zeros or similar, some terminal programs would speed past that part of the disk so to speak. Data compression on the fly and all. And at 300 baud back then it was a big deal. A huge deal even! At night it would mean the difference between getting 1, 2, 3, or sometimes more games depending on sizes. Obviously the smaller the better.

 

I even remember that Cat-Fur and/or Cat-Send had a utility to zero out unused sectors. And of course DDD and other disk packers did the same thing.

 

Why worry about shit like this today? Well just because! And it's amusing to say that a number of disk images can fit entirely within the L2 or even L1 cache of a modern CPU when doing emulation. Just trivia, but interesting and comparative trivia nonetheless.

 

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Didn't the Copy ][ Utilities has this feature??

 

 

MarkO

 

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I'm not aware that it did. Unless it's been in one specific version and no others. The utilities can sort the catalog or do a disk map, or a full-disk format. But I think that's it.

 

 

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