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 Post subject: Difficult Disk Format
PostPosted: March 27th, 2014, 5:38 pm 
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I have 3 disks - 2 Epson Disk Basic and the game King Salmon - I have been trying to dump on the Kryoflux. These disks seem to have:

- Side 0 Track 0 FM encoded, 26 data sectors of 128 bytes ( dumped to file 1 ).
- Side 1 Track 0 to 77, Side 0 track 1 to 77 ( ie: all the rest ), MFM encoded, 26 sectors of 256 bytes ( dumped to file 2 ).

Has anyone any advice as to how to piece these together into something usable in an emulator?

:?:


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PostPosted: March 29th, 2014, 7:37 am 
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Ho ho ho! Some progress.


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PostPosted: March 29th, 2014, 2:44 pm 
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I have done a huge fiddle to get these going, and I would appreciate anyone's help to see if the disk images work correctly, especially the game.
They run ONLY in Next, and in fairly new versions - mine is dated 2010/05/23 out of the Neo Kobe Pack of 2013/08/17.
No other emulator I have tried works, probably because of the variable sized sectoring.

To save having to code a new program ( it might come to that ) I:
- created an empty file exactly of the size 2 heads, 77 tracks, 26 sectors, 256 bytes/sec to file(1)
- used the HxC software to create a .d88
- for each disk, dumped track 0 head 0 to a file(A), padded using hex editor to correct length, used HxC to create a .d88
- for each disk, dumped the rest to a file(B), padded using hex editor to correct length, used HxC to create a .d88
- assembled a .d88 out of the .d88 header of file(1), first track data of File(A), padding of H"00"s, rest of tracks from file(B)

The only real funny is the extra padding of H"00"s at the end of the first track. Given the .d88 structure, the track pointers are all correct, and the sector data and lengths are also correct.

Effectively an image with 26*128bytes/sector for track 0 head 0, then 26*256bytes/sector for the rest. This is different to most PC98 disks which have consistent 1024 byte sectors.

I am also open to ideas and suggestions, and corrections. Thanks.

http://www.retroprograms.com/temp/EpsonBasic_Salmon.7z

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PS - what are the 2 Epson disks - ie: what is the text below the Disk Basic?


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PostPosted: March 29th, 2014, 6:05 pm 
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UPDATE!

I changed the media descriptor to 2HD, which it probably should have been, and they now run in Neko.

I have re-uploaded the archive with 2HD versions - please redownload if you have got it already.

Progress progresses! :D


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PostPosted: April 2nd, 2014, 5:31 am 
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Thanks for all the hard work peter_j. Sorry I didn't have time to help troubleshoot these disks (not that you needed any help in the end :) )
For the Epson disks, the one on the left is the Utility Disk (ユーティリティディスク), the one on the right is the System Disk (システムディスク).

In your files, epsona is the Utility disk. Launch by typing
Code:
run"bmenu"

epsonb is the system disk. But I'm not sure what it's supposed to contain.

King Salmon works, but you need a formatted user disk in the second drive (I just used a copy of epsonb).


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PostPosted: April 2nd, 2014, 4:36 pm 
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Thanks for the help kobushi. :D


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