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vedos
Account closed
Registered: Jul 2003
Posts: 33 |
C-64 formatting program which supports multiple disk drives simultaneously and has proper error checking
Can anyone recommend me a good disk formatting program for C-64 (I'm using 1541 and 1541-II drives) which supports multiple disk drives (preferrably simultaneously) and has a proper disk error detection (as far as I've understood eg. Action Replay MK VI's format doesn't check for disk errors). The speed isn't that important. I just want to format working disks. :) |
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Skate
Registered: Jul 2003
Posts: 490 |
@Groepaz: did you read my message to the end? I say it's not necessery to make an error check until you finish copying your files. quick format, copy, then check for errors. even if your disk is damaged but your files are not covering that track/sector, hell with that error. |
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Oswald
Registered: Apr 2002
Posts: 5017 |
I hate to say it, but groppie is kinda right here :) |
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SIDWAVE
Account closed
Registered: Apr 2002
Posts: 2238 |
Fast Hack'em, worked since 1985 |
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Krill
Registered: Apr 2002
Posts: 2845 |
Quote: Fast Hack'em, worked since 1985
Which version are you referring to? I found none which has a multi-drive formatter. |
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chatGPZ
Registered: Dec 2001
Posts: 11116 |
Quote:Groepaz: did you read my message to the end? I say it's not necessery to make an error check until you finish copying your files. quick format, copy, then check for errors. even if your disk is damaged but your files are not covering that track/sector, hell with that error.
its not that easy unfortunately. as long as you are never going to write again to that disk, then everything is fine. (thats why many people dont remember AR fastformat as problematic). the problems arise whenever you are going to write something to the disk.... because:
a proper format routine as a first step determines how many bit cells can be written to a track in one rotation (the duration of a bit cell it can write is fixed, but the rotation speed is not). now it calculates the number of padding bytes that must be used to fill the various gaps on the track. many fastformatters skip this step completely and use hardcoded values for an assumed rotation speed of 300rpm. (and this is what saves a lot of time, its not the verify of actual written blocks - that can be done in a single additional rotation).
and this is why omitting the above eventually becomes a problem:
assume you ar fast-formatted a disk on a drive that spins slightly slower than 300rpm. the consequence would be that all gaps are slightly shorter on the medium than they should be. now you put this disk into a drive which is slightly faster than 300rpm.... you can read the disk fine, no problem. but when writing to the disk all hell breaks lose: when writing a block, the drive looks for the sector header, and when the sector is found waits until the data block comes by, switches to write mode and then writes out a full block. due to the analog nature of the media (rotation speed is not fixed) the actual physical area on disk which represents this written sector doesnt always perfectly match the old same sector, but "moves back and forth" a bit - thats why the padding gaps between data blocks and sector headers exist. now remember, the drive we are using is a bit too fast, and this very gap is a bit too short. what eventually happens now is that the data block overwrites the sync mark before the following sector header - resulting in that sector beeing unreadable (sector header not found).
and thats why a proper format routine is win :) |
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Oswald
Registered: Apr 2002
Posts: 5017 |
now up it to codebase :) |
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tlr
Registered: Sep 2003
Posts: 1714 |
@groepaz: Well said!
In my practical experience most drives have been close to 300 rpm but that's not guaranteed. Also many fast formatters (including my older one) assume the same static gap for all speed zones. Some (e.g jiffy dos) assume different static gaps for each speed zone which is slightly better.
Whereas the normal 1541 formatter measures track length for each track, the speed dos+ formatter improves speed by only measuring the track length once per speed zone.
I have done a prototype formatter that only measures track length once per format and then scales the value for each speed zone. That seems to work quite well.
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The Shadow
Registered: Oct 2007
Posts: 304 |
The fast format in Fast Hack 'Em can be found in the file copier. |
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tlr
Registered: Sep 2003
Posts: 1714 |
Quote: The fast format in Fast Hack 'Em can be found in the file copier.
I checked the one in this release: Single File Hack'em.
It is the typical static intersector gap=8 without verify.
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Mace
Registered: May 2002
Posts: 1799 |
@ Groepaz: thanks for the insight :-)
Not that I can make any use of this information, but I like reading about it...
BTW, mind the 'goof' of Single File Hack 'em. |
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