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Old 12 March 2017, 00:22   #11
Pat the Cat

Join Date: Dec 2016
Location: Nottingham, UK
Posts: 481
Originally Posted by Daedalus View Post
Nope, you simply don't understand what MaxTransfer is. MaxTransfer specifies the maximum size of any data transfer carried out by the relevant driver. It doesn't have anything to do with the buffering of the port, or the memory used, or the speed of the transfer, or the lag, or any shadowing of any ROM, or a 16 or 32-bit data bus.

Normally a device driver will automatically take care of the maximum transfer possible by splitting large requests into smaller chunks that can be safely handled without corruption, but the scsi.device used on the A600, A1200 and A4000 doesn't do this, which causes corruption if any transfers are carried out that are larger than ~128KB (0x1FE00). Setting the MaxTransfer to that value or lower simply tells the driver to manually split larger transfers into multiple operations instead5 of one, thus avoiding corruption.
So the MaxTransfer value (the setting, not the rate as I had already posted) can indeed mangle large files like ROM dumps, and if the OP sets a lower value of Max Transfer on the drive (as I have suggested) and recopies the files to the drive, that might resolve the issue.

If it was purely a software issue, you would think it would have been sorted after 25 years, and if you think it's just a software issue, feel free to rewrite scsi.device to fix it.
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