FM Towns disc, C2 Error

[fuzzball]

Is there anything I can try?
I've tried low speed (x4).
The disc looks clean.

dic_20200921T112141.txt

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..\Release_ANSI\DiscImageCreator cd G .\dic 20 /c2 20 

dic_c2Error.txt:

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                 ofs: 160, 161, 162, 163, 168, 169, 16a, 16b, 18c, 18d, 18e, 18f, 194, 195, 196, 197, 19c, 19d, 19e, 19f, 
 LBA[110740, 0x1b094] Detected C2 error 20 bit
LBA[110740, 0x1b094]: crc32[000]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[001]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[002]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[003]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[004]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[005]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[006]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[007]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[008]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[009]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[010]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[011]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[012]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[013]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[014]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[015]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[016]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[017]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[018]: 0x58c26c62 bad
LBA[110740, 0x1b094]: crc32[019]: 0x58c26c62 
bad all. need to reread more

[sadikyo]

It sounds counterintuitive, but try a higher speed, or try a lower speed and change /c2 20 to something like /c2 200 to give it more attempts. 

If the disc looks really clean with no identifiable scratches, give it a few more attempts at different speeds and you might have some success.

[fuzzball]

It sounds counterintuitive, but try a higher speed, or try a lower speed and change /c2 20 to something like /c2 200 to give it more attempts. 

Thanks, I've tried different speeds and the results are the same. (x1, x2, x3, x16, x32, x40, x48 and /c2 200)
I’m going to give it a rest.

[sadikyo]

How many sectors are detected as bad?  Is it just 110740 or is it many of them?

Unfortunately there are a lot of variables here - do you have another drive to test it on?  Even a non-plextor / non-redump drive just to see if it can read/dump the disc with no errors/unreadable sectors?  It's also possible it is a mastering issue.

[fuzzball]

It's only 110740.
logs: https://www.dropbox.com/s/3oavpkdsfbn82zs

The other drives do not work with DIC.

[wiggy2k]

Eikan 3?

I have the same disc with the same error.
is always a 20 or 24bit error.
Disc is immaculate.

from my logs:

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 LBA[110740, 0x1b094] Detected C2 error 24 bit
LBA[110740, 0x1b094]: crc32[000]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[001]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[002]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[003]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[004]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[005]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[006]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[007]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[008]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[009]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[010]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[011]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[012]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[013]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[014]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[015]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[016]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[017]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[018]: 0x01e0d279 bad
LBA[110740, 0x1b094]: crc32[019]: 0x01e0d279 

[reentrant]

Check c2 file. If the pattern is F0F0F0 and 0F0F0F it means it's known Plextor firmware bug. Use different drive to get the data and replace it with hex editor.

[F1ReB4LL]

https://github.com/saramibreak/DiscImag … e8d6a04ec4 - added: ignoring "F0 F0 F0 00 00 00 0F 0F 0F 0F" of C2 error

And what we have here are the "F0 F0 F0 00 00 00 0F 0F 0F" sequences detected as 24 bit (or 12 bit + 12 bit or 8 bit + 16 bit errors depending on how the data is shifted on different drives).

https://www.sendspace.com/file/zsmiqz - wiggy's and coolmod's logs (Premium and 5024 logs aren't included because they match 716, BH16NS40 logs aren't available because it was only tested with ImgBurn).

But different drives give different data for the audio tracks affected by these. PX-716A, Plextor Premium and one more Plextor model (wiggy named the folder "5024", but he doesn't have SCSI drives, so it's not DM-5024 and probably he meant PX-W5224) dumps match, PX-W4012A dumps differ, LG GSA-H10N detects no C2 errors and its dumps differ again; and it seems that BH16NS40 drive dumps also differ (needs more testing). So I don't know how to choose a good dump (and if any of the dumps is good).

sarami: https://www.mercari.com/jp/items/m58911186185/ - Eikan wa Kimi ni 3 if you want to buy the disc for yourself to test.

[sarami]

https://www.sendspace.com/file/zsmiqz - wiggy's and coolmod's logs (Premium and 5024 logs aren't included because they match 716, BH16NS40 logs aren't available because it was only tested with ImgBurn).

I tried by PX-760, 755, 5224, 4824 and Asus BW-16D1HT 3.02 (0xf1 drive).
760, 755, 5224 are the same as their 716 logs.

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    <rom name="zzzz (Track 09).bin" size="2074464" crc="2cf046de" md5="98cf9dba1cf9b28a493082d91f5423e8" sha1="4fed081b9f0a5d30366581fd2949a1bb203af5f4" />

4824 is the same as their 4012 logs

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    <rom name="zzzz (Track 09).bin" size="2074464" crc="e79c85f0" md5="40fa8f9c224ace448e4252d045439ffd" sha1="c767b1b8ca90b600336fda4ba34f166fe2f9f818" />

My 760, 755, 5224, 4824 also output "F0 F0 F0 00 00 00 0F 0F 0F"

BW-16D1HT
No C2 errors

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    <rom name="zzzz (Track 09).bin" size="2074464" crc="99ca4c2c" md5="e18db5659845f60784e9437823f42003" sha1="b5f44230135e50b56ab6a8cd257b29e329b88bb3" />

This phenomenon looks like Puzzle Bobble 4 of Dreamcast.

If BW-16D1HT is true, it's also true that plextors output these c2 errors? But plextors can't fix these errors.

[reentrant]

All my plextors spit these C2 errors and none of my non-plextor drives do so. In such cases I use data command from two different non-plextor drives and manually patch & compare the tracks. It's unfixable on plextors.

Many Polish discs from 2000-2002 with -153 write offset suffer from this bug.