dsk file works great on emulator but crasch when copy on disk with ADTPro

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Last seen: 3 months 2 weeks ago
Joined: Oct 17 2023 - 05:38
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dsk file works great on emulator but crasch when copy on disk with ADTPro

Hi All,

I have downloaded this DSK file, an open version provided by the author on his web page:

HTTP : // www.erix.it / retro / cast2001.zip


inside the zip file, there is the game with the name C201.dsk. If you load it from an emulator (like Virtual II on Mac), it works perfectly! But when you transfer it with ADTPro on a real floppy to use it on Apple//c at boot time you reach an I/O error!

I try to check the disk and files with the Dos 3.3 utility but no errors are discovered!

someone has an idea of how to solve it and create a working copy on a floppy!





Last seen: 7 hours 4 min ago
Joined: Nov 29 2020 - 19:48
Posts: 130
Bad spot on the floppy?

IO error means a  block of data has failed to read or write.  That could be because the floppy has one or more blocks of data which have physically failed, or because the floppy drive has some mechanical flaw,  or is out of speed tolerance if you used different floppies to create and then read the data. I would suspect a bad spot on the floppy as the most likely cause.

#1 You might try Copy ][+ to verify or to copy the disk.  It would show a track and sector error where the read failed and confirm a bad block on defective media. 

#2 Perhaps using ADT Pro to create prepare a different floppy diskette might work. 

#3 Since the .dsk file works in Virtual ][ we would assume the source image is correct, simply making a duplicate copy of the file with a different name on the dsk would give you a second copy on the floppy which occupies different data blocks. If you only have one floppy diskette, using ADT Pro to recreate the floppy might let you read the second copy, assuming those blocks are good.

#4 You did not mention the file type or how you are trying to execute the program.  If it a basic program, not binary,  can you LIST the code?  Does it end abruptly or does it appear to be complete with a natural ending?  You might be able to RUN it manually, even though DOS reports an I/O Error.

You definitly want to rule out a bad floppy disk before chasing down possible drive or RAM failures.  The bad diskette it by far the most likely issue.


Last seen: 3 months 2 weeks ago
Joined: Oct 17 2023 - 05:38
Posts: 2
Hi I try with different
I try with different floppy, after the disk trasfer I test with dos utility and disk and file are correct no errors. The Strange think if I do the inverse process and create a new .dsk file on computer from the disk and I try to execute in emulatore work fine with no erros. 
I already copy other sdk file and all work fine with no errors, only this one have the issue.
mmphosis's picture
Last seen: 2 weeks 5 hours ago
Joined: Aug 18 2005 - 16:26
Posts: 434
.dsk files with the emulator

.dsk files with the emulator could be a related issue? It has to do with the sector ordering between DOS 3.3 and ProDOS. There are .do and .po extensions to hopefuly distuish the different sector ordering when using an emulator.

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