[HN Gopher] PC Floppy Copy Protection: Xemag Xelok
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       PC Floppy Copy Protection: Xemag Xelok
        
       Author : GloriousCow
       Score  : 6 points
       Date   : 2024-10-06 17:32 UTC (5 hours ago)
        
 (HTM) web link (martypc.blogspot.com)
 (TXT) w3m dump (martypc.blogspot.com)
        
       | GloriousCow wrote:
       | In this post in a series on PC copy floppy protections, we take a
       | look at XEMAG duplication's "Xelok" scheme.
       | 
       | Xelok was quite devious on the Apple II, implementing "fat
       | tracks" that could not be produced with a conventional disk
       | drive. However the PC doesn't allow such tricks, so Xelok appears
       | a bit different on the PC platform.
       | 
       | We take a look at two titles that use it, Sargon III and The
       | Ancient Art of War.
       | 
       | We also take note of a rather amusing bypass for this protection!
        
       | ksaj wrote:
       | I find it humourous that their logo looks like what happens when
       | older generations of Windows failed on popups.
        
         | GloriousCow wrote:
         | Or when you win solitaire!
        
       | somat wrote:
       | Probably a silly question. but are those images of a disks layout
       | high enough resolution to recreate the disk?
       | 
       | I know it's silly because if you wanted to encode a disk image
       | such that it works as a png you would not use a circular layout.
       | Too many weird angles, it would make it harder than it needs to
       | be to reconstruct.
        
         | GloriousCow wrote:
         | For the ones that I make to look pretty, the data is colored in
         | buckets of 8 bits, using the bit-count per byte to select a
         | shade in 8 steps from 0-255. So there's at least 8 times less
         | data than you would need. Then it is downsampled 4x to get nice
         | antialiasing, so that is more data loss.
         | 
         | I do have a bit-mode, and if you rendered at high enough
         | resolution you could do it, maybe something like 32k x 32k. But
         | this is a very inefficient way to store a disk image. :)
        
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       (page generated 2024-10-06 23:01 UTC)