visualize_1541 is a tool that creates visualizations of the data layout on G64 Commodore 1541 disk images.
This representation is useful to visualize custom disk formats and differences in gap sizes.
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Every track starts at the bottom and is drawn counter-clockwise.
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Green represents the data. Darker areas have more 0-bits.
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Red represents a longer sequence of 1-bits.
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Blue represents a longer sequence of 0-bits.
python visualize_1541.py disk.g64 disk.png
This representation is useful to visualize errors on Commodore-formatted disks. The tool decodes SYNC marks and sector headers.
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Every pack of 17-21 lines is a track, numbered 1-41.
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Every line within a pack is one sector.
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The raw sector contents are drawn from left to right.
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The cyan part is the header, the green part the data.
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Black is 0, cyan/green is 1.
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White represents missing header or sector sections.
python visualize_1541_blocks.py disk.g64 disk.png
A JavaScript version by Jaime Idolpx is also available. Open visualize_1541.html in a browser and select a .g64 file to visualize, or try it online at https://pagetable.com/docs/visualize_1541/.
There are two articles about these tools:
These are some limitations of the tool for the circular representation:
- Because the Pillow library cannot draw antialiased lines, the tool renders the image at 16x (!) the resolution and scales it down at the end. This uses a lot of memory, yet there are still Moiré artifacts. Using a different image library would be a good idea.
- Red areas (SYNCs marks) show up as soon as there are 8 1-bits. SYNC detection on the 1541 requires at least 10. (The sector-by-sector tool contains logic for correct SYNC detection that should be ported over.)
- The data area shows the GCR data. An option should be added to show the GCR-decoded data.
nibtool.nbzfiles are better suited as sources, the tool should be extended to support them.
Michael Steil mist64@mac.com, https://www.pagetable.com/