Bug in DiscFerret (.DFI) image read support

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philpem
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Joined: Sat Jan 30, 2021 10:42 pm

Bug in DiscFerret (.DFI) image read support

Post by philpem »

I'm testing with the HxC Floppy Emulator v2.5.6.7 software.

I've found that while HxCFloppyEmulator will read DiscFerret images, this only works for ones recorded with a clock rate of 100MHz.

If a 50MHz-clocked or 25MHz-clocked image is loaded in, HxC will incorrectly convert the bit times and disc RPM.
For 50MHz images the RPM is reported as 600RPM (instead of 300)
For 25MHz images the RPM is reported as 1200RPM (instead of 300)

While DFI files don't include the clock data as part of the format, this can be solved in two ways --

- Guess based on the timing between index pulses. There are only three valid clock rates (25MHz, 50MHz and 100MHz). The correct rate will be the one which produces a disc RPM of 300RPM or 360RPM.
- Ask the user for the correct clock rate. (This should ideally always be an option -- "force DFI image clock rate to...")

I'm working on a tool to 're-clock' DiscFerret images to 100MHz clock -- but it would still be useful to have this bug fixed in HxC to avoid the need for the re-clocking step.

Thanks.
Phil.

Jeff
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Re: Bug in DiscFerret (.DFI) image read support

Post by Jeff »

I wasn't aware that 50MHz and 25MHz DFI even exist. So the only way to "detect" them is to check the index timing ? I don't like this idea because 600RPM drives is a valid index period too...
I think i will just add a parameter for this.

Jeff
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Re: Bug in DiscFerret (.DFI) image read support

Post by Jeff »

New beta version (windows) :

https://hxc2001.com/download/floppy_dri ... t_beta.zip

Change the "DFILOADER_SAMPLE_FREQUENCY_MHZ" value.

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