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davidgiven
Can't correctly write mac400 with Greaseweazle
Writing 400K single sided disks using a Greaseweazle (firmware 1.1) appears to be partially broken. The resulting disks can be read in 800K drives but not in 400K drives.
Are you Tube Time on Twitter (who just reported the same thing)? https://twitter.com/hjalfi/status/1561325934204096512
I have actually recently observed this happening on the Brother 120kB format, but I don't know why --- I've tried going back through the revision history and haven't been able to track down why. The recent addition of the flux explorer was supposed to help debug this, but didn't.
Yep, that's me.
On Mon, Aug 22, 2022, 7:50 AM David Given @.***> wrote:
Are you Tube Time on Twitter (who just reported the same thing)? https://twitter.com/hjalfi/status/1561325934204096512
I have actually recently observed this happening on the Brother 120kB format, but I don't know why --- I've tried going back through the revision history and haven't been able to track down why. The recent addition of the flux explorer was supposed to help debug this, but didn't.
— Reply to this email directly, view it on GitHub https://github.com/davidgiven/fluxengine/issues/559#issuecomment-1222470250, or unsubscribe https://github.com/notifications/unsubscribe-auth/AALD7RUWW724DENYS64PR2LV2OHUNANCNFSM57D6X3IQ . You are receiving this because you authored the thread.Message ID: @.***>
Oh, good! That means there's only two people being annoyed by this --- you and me...
I couldn't find any differences when comparing Brother tracks with FluxEngine tracks, so it's nice that you have. I'll see if I can duplicate that my my own flux visualiser, but until then, did you find anything more out on where the difference is?
i have not had a chance to dig into it in any more detail other than the screen shots on Twitter. would it help you to see the two SCP files? one is an original 400K blank floppy formatted by the Mac, and the other is the flux image after being round-tripped through Fluxengine. (first flux image written by Fluxengine to a disk and then read back.)
I've just realised that Mac 400kB disks are not 40-track --- they're single sided 80 track. So this is likely to be a different problem. I wonder if the Macs are detecting data on the second side and getting confused (they shouldn't be).
I'll get my Mac out and see if I can duplicate this myself.
My Mac can't format 400kB disks. Yes, please, send me the SCP files! (You should be able to attach them to the bug.)
Sorry for the delay --- but I've finally got around to looking at this...
I can see that the clock rate on the two disks is slightly different, as well as the sector skew. I'll see if I can fix that and get back to you. Did you get anywhere yourself?