disk images: graphical images of data layout on disk

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BigEd
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disk images: graphical images of data layout on disk

Post by BigEd » Sun Jan 07, 2018 7:48 pm

An interesting series of tweets from Paul Rickards, visualising some C64 disks.
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Commie_User
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Re: disk images: graphical images of data layout on disk

Post by Commie_User » Sat Jan 20, 2018 1:58 pm

What do the coloured bits represent? They must be bytes.

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danielj
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Re: disk images: graphical images of data layout on disk

Post by danielj » Sun Jan 21, 2018 7:46 am

Flux transitions. It's the distance between these that are translated into bits, and consequently bytes :)

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jms2
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Re: disk images: graphical images of data layout on disk

Post by jms2 » Sun Jan 21, 2018 9:48 am

Interesting and pretty! I like it.

Perhaps it's an illusion, but there doesn't look to be anything like enough colour variations to represent the number of bits that would be on a disk. That said, how much capacity is there on a c64 disk?

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topcat96
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Re: disk images: graphical images of data layout on disk

Post by topcat96 » Sun Jan 21, 2018 10:18 am

jms2 wrote:That said, how much capacity is there on a c64 disk?
The 170 kB disc is split into 683 sectors on 35 tracks, each of the sectors holding 256 bytes. However, one track is reserved by DOS for directory and file allocation information (the BAM, block availability map).
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Re: disk images: graphical images of data layout on disk

Post by Commie_User » Mon Jan 22, 2018 2:51 pm

I'm still amazed and humbled that programmers got so much with so little for our computers, not just the 64 of course. Arty programs and games still come across differently from what's out today and even Mayhem In Monsterland was released on PSP with only a wider panorama.


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All of that just from on there.

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Re: disk images: graphical images of data layout on disk

Post by Commie_User » Mon Jan 22, 2018 2:58 pm

topcat96 wrote:The 170 kB disc is split into 683 sectors on 35 tracks, each of the sectors holding 256 bytes.
A D64 disk image comes out at 171K, while a G64 disk image comes out more. I don't know what the extra 1K is for (error logs?) but the Web says the bigger G64 image is for archives where the 64 program wants to read and write the disk in an 'unconventional' way. Further information's just Greek to me but it's lucky for me the original hardware worked to a standard size unless physically upgraded.

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danielj
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Re: disk images: graphical images of data layout on disk

Post by danielj » Mon Jan 22, 2018 3:16 pm

G64 contains information about how the data were written, its good for protected disc formats and there's enough info in the file to recreate the original disc.

d.

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Re: disk images: graphical images of data layout on disk

Post by Commie_User » Mon Jan 22, 2018 4:08 pm

Ah. Thank you.

There was a niggle in my brain - among all the others - about how the original equipment worked just fine with the original disk size if there wasn't any more actual program data.

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